Vaporizer and Gas Chromatograph

Abstract

To provide a vaporizer capable of completely vaporizing a sample by a heating module while avoiding the buildup of pressure in the sample after vaporization, and a gas chromatograph equipped with the vaporizer. The vaporizer (100) is used for sample pretreatment in a gas chromatograph (200) and includes an inlet (1), a gas sample outlet (2), a heating module (3), and a current limiting device (4). The heating module is connected to both the inlet and the gas sample outlet, and flash-vaporizes the liquid sample from the inlet into a gas sample, which is then transported to the gas chromatograph via the gas sample outlet. The vaporizer includes a current limiting device in the line between the heating module and the inlet.

Description

[Technical Field]

[0001] The present invention relates to the field of analytical technology, and more particularly to a vaporizer and a gas chromatograph equipped with the same. [Background technology]

[0002] In some test detection and analysis sites, for example when analyzing samples by gas chromatography, a pretreatment is required to vaporize the liquid sample into a gas sample, which is then detected and analyzed as the gas sample.

[0003] Conventional vaporization methods generally involve flash vaporization of a liquid sample using a heating module, followed by adjustment of the gas flow rate using a needle valve or solenoid valve. However, because the volume of the liquid expands approximately 1,000 times after vaporization, even a small amount of liquid sample generates a very large volume of gas. Furthermore, the flow rate of the vaporized sample gas is restricted, creating pressure buildup that exceeds atmospheric pressure, making it easier for high-boiling-point gas components to condense after vaporization. Alternatively, a vaporization temperature higher than atmospheric pressure is required to ensure the vaporization of high-boiling-point components, which can lead to the decomposition or denaturation of temperature-sensitive components. Summary of the Invention [Problem to be solved by the invention]

[0004] In response to the above problems, the present invention provides a vaporizer and a gas chromatograph equipped with the vaporizer, which can avoid the buildup of pressure in the vaporized sample and completely vaporize the sample using a heating module. [Means for solving the problem]

[0005] One aspect of the present invention provides a vaporizer applicable to sample pretreatment in a gas chromatograph, comprising an inlet, a gas sample outlet, a heating module, and a flow-limiting device. The heating module is connected to both the inlet and the gas sample outlet, and flash-vaporizes a liquid sample from the inlet into a gas sample, which is then transported to the gas chromatograph via the gas sample outlet. In particular, the vaporizer of the present invention further comprises a flow-limiting device disposed in a conduit between the heating module and the inlet, the flow-limiting device having an adjustable flow rate.

[0006] According to the technical solution of this invention, a liquid sample enters the vaporizer through the inlet, is limited to a small flow rate by a current-limiting device, enters the heating module, and is flash-vaporized into a vaporized gas sample, which is then transported to the gas chromatograph through the gas sample outlet. By controlling the current-limiting device, the flow rate of the liquid sample into the heating module can be controlled to ensure complete vaporization of the liquid sample entering the heating module. Since the current-limiting device is installed before the heating module and its flow rate is adjustable, not only can the flow rate of the gas sample be adjusted, but the vaporized sample will not be overpressurized.

[0007] In a preferred technical solution, the current limiting device includes a variable current limiter, a fixed current limiter, a flow meter, and a controller, wherein the fixed current limiter and the variable current limiter are connected in series with each other. The flow meter is used to detect the flow rate in the pipeline in which the current limiting device is installed. The controller is communicatively connected to the flow meter and the variable current limiter, respectively, and adjusts the opening degree of the variable current limiter based on the flow rate detected by the flow meter.

[0008] According to this preferred technical solution, because liquid standard samples are usually expensive and their volume expands after vaporization, very little liquid sample is required for analysis, and the liquid flow rate that needs to be controlled is very low. However, this is difficult to achieve with current variable current limiters, and even if possible, their service life is shortened. However, while fixed current limiters can continuously control the liquid flow rate at a low level, they cannot adjust the liquid sample flow rate, which causes unstable flow rates of liquid samples under different pressures and impairs the consistency of subsequent sampling. Therefore, by connecting a variable current limiter and a fixed current limiter in series, the liquid sample supply flow rate to the heating module can be controllably adjusted while improving the service life of the current limiter.

[0009] The flow rate of the vaporized gas sample can be monitored using a flow meter, and by linking this with the control of the variable flow limiter by the controller, the flow rate of the gas sample transported to the gas chromatograph via the gas sample outlet can be controlled with high precision.

[0010] In a preferred technical solution, the variable current limiter is a needle valve, and the fixed current limiter is a damper tube.

[0011] According to this preferred technical solution, the flow rate of the liquid sample is adjusted by combining a needle valve and a damper tube, so that the needle valve can adjust to a small liquid flow rate with a relatively large opening, thereby extending the life of the needle valve, reducing costs, or facilitating the customization of needle valves with smaller flow rate specifications.

[0012] In a preferred technical solution, the vaporizer further includes a tracing tube, and the vaporizer is connected to the gas chromatograph through the tracing tube, and the tracing tube has a gas sample outlet line whose both ends are connected to the heating module and the gas sample outlet, respectively.

[0013] According to this preferred technical solution, the gas sample that has passed through the heating module passes through a tracing tube before entering the gas chromatograph, which can better ensure that the vaporized sample does not condense and improve the detection accuracy.

[0014] In a preferred technical solution, the vaporizer further includes an exhaust port, and the tracing tube further has a return air flow path, one end of which is connected to the sample outlet of the gas chromatograph to receive the gas sample returned from the gas chromatograph, and the other end of which is connected to the exhaust port via a flow meter.

[0015] According to this preferred technical solution, the gas sample at the outlet of the gas chromatograph is introduced into the flow meter via a tracing tube, thereby avoiding the effects of the dead volume of the flow meter and unavoidable small leaks, and reducing the purging time each time sampling is performed.

[0016] In a preferred technical solution, the flow meter is a float type flow meter.

[0017] In a preferred technical solution, the vaporizer further includes an electrically operated shut-off valve disposed between the current limiting device and the inlet and communicatively connected to the controller.

[0018] According to this preferred technical solution, the controller controls the electric shut-off valve, which can quickly start / stop the injection of the liquid sample, eliminating the need for manual operation, saving manpower, and making the operation convenient and fast.

[0019] In a preferred technical solution, the injection port includes a liquid sample inlet and a gas sample inlet, and the vaporizer further includes a two-way valve and a three-way valve, the two-way valve communicating with an exhaust port, and the three-way valve having one side alternatively communicating with either the liquid sample inlet or the gas sample inlet and the other side communicating with both the motorized shut-off valve and the two-way valve.

[0020] According to this preferred technical solution, the three-way valve allows for selective introduction of either a liquid or gas sample, enabling a single vaporizer to be used for both liquid and gas sample introduction and analysis. Furthermore, the two-way valve communicates with the exhaust port, facilitating purging of the line from the inlet to the exhaust port and preventing residue from the previous sample.

[0021] In a preferred technical solution, the vaporizer further includes a filter disposed between the three-way valve and the motorized shutoff valve.

[0022] According to this preferred technical solution, the filter can filter out impurities such as solid particles in the liquid sample to avoid clogging the downstream current limiting device.

[0023] A second aspect of the present invention provides a gas chromatograph including a vaporizer according to any of the above technical solutions. [Brief explanation of the drawings]

[0024] [Figure 1] 1 is a structural schematic diagram of a vaporizer according to an embodiment of the present invention; [Figure 2] 1 is a structural schematic diagram of a preferred current limiting device according to an embodiment of the present invention; [Figure 3] 1 is a structural schematic diagram of a preferred vaporizer according to an embodiment of the present invention; DETAILED DESCRIPTION OF THE INVENTION

[0025] The technical solutions in the embodiments of the present invention will be clearly and completely explained below with reference to the drawings of the embodiments of the present invention, and the embodiments mentioned are only a part of the embodiments of the present invention and are not exhaustive. All other embodiments that can be obtained by those skilled in the art based on the embodiments of the present invention without any creative work are all included in the scope of protection of the present invention. First embodiment

[0026] 1 is a structural diagram of a vaporizer according to an embodiment of the present invention. As shown in FIG. 1, the vaporizer 100 includes an inlet 1, a gas sample outlet 2, a heating module 3, and a current limiting device 4. Here, the inlet 1 includes at least a liquid sample inlet 1, through which a technician can inject a liquid sample into the vaporizer 100, or the inlet 1 can also work in conjunction with a quantitative extraction device such as a volumetric pump, thereby automatically injecting a quantitative amount and enabling better control of the volume of the injected liquid sample.

[0027] The heating module 3 is provided in the pipeline downstream of the inlet 1. The heating module 3 may be an electric heater or a heat exchanger, but is not limited thereto. Generally, the heating module 3 is preferably configured to be able to encase and heat a long pipeline. For example, the heating module 3 may be an electric heating box, and the pipeline downstream of the sampling is spirally arranged inside the electric heating box. The liquid sample entering through the inlet 1 is rapidly heated and vaporized inside the heating box along the pipeline. The vaporized gas sample finally flows out from the outlet of the heating box and is then transported to the gas chromatograph 200 via the gas sample outlet 2.

[0028] In particular, the vaporizer 100 further includes a current limiting device 4, which is provided in the conduit between the heating module 3 and the inlet 1 and has an adjustable flow rate. Here, the current limiting device 4 may be any device that can limit the flow rate of the liquid sample to an adjustable predetermined value or range of values. The value or range of values ​​may be preset according to the power of the heating module 3, and is set to a value or range of values ​​that allows the heating module 3 to vaporize the entire liquid sample while avoiding any impact on detection efficiency.

[0029] In a preferred embodiment, the vaporizer 100 may further include an electric shut-off valve 5 (see FIG. 3) disposed between the current limiting device 4 and the inlet 1 and communicatively connected to the controller 44. By controlling the electric shut-off valve 5 with the controller 44, the injection of the liquid sample can be quickly started / stopped, eliminating the need for manual operation, saving manpower, and making operation convenient and quick.

[0030] Specifically, a liquid sample enters the vaporizer 100 through the inlet 1, is limited to a small flow rate by the flow limiting device 4, the liquid sample enters the heating module 3 and is flash vaporized into a vaporized gas sample, and the gas sample is transported to the gas chromatograph 200 through the gas sample outlet 2.

[0031] In this embodiment, the current limiting device 4 controls the flow rate of the liquid sample into the heating module 3 so that the liquid sample entering the heating module 3 can be completely vaporized, and since the current limiting device 4 is installed in front of the heating module 3, not only can the flow rate of the gas sample be adjusted, but the pressure of the sample after vaporization is also prevented from building up. Second embodiment

[0032] 2 is a structural schematic diagram of a preferred current limiting device according to an embodiment of the present invention. As shown in FIG. 2, compared with the first embodiment, this embodiment provides a more detailed structure of the current limiting device 4, which includes a variable current limiter 41, a fixed current limiter 42, a flow meter 43, and a controller 44.

[0033] Here, the fixed current limiter 42 and the variable current limiter 41 are arranged in series between the inlet 1 and the heating unit. The fixed current limiter 42 refers to a current limiter that can quantitatively reduce the flow rate of the liquid but cannot adjust the amount, such as a pressure-drop type current limiter such as a damper tube. The variable current limiter 41 refers to a current limiter that can adjust the amount of flow through by adjusting the valve opening, such as an aperture-controlled current limiter such as a needle valve. Note that the variable current limiter 41, such as a needle valve, controls the amount of flow through the liquid sample by controlling the aperture. If the aperture is too small, the pressure upstream of the valve increases, which may shorten the service life of the valve or even cause damage.

[0034] Because liquid standards are usually expensive and expand in volume after vaporization, the amount of liquid sample required to perform the analysis is very small, and the liquid flow rate must be controlled to a very low level (in some embodiments, the liquid sample flow rate must be controlled to 0.2 mL / min or less).

[0035] It is difficult for conventional variable current limiters 41 to achieve extremely low flow rate control based on the current limiting principle of variable current limiter 41, and even if such control is achieved, the opening must be kept extremely small. For example, in the case of a needle valve, even the needle valve currently on the market with the smallest controllable flow rate can barely achieve this with an opening of less than one revolution, but such a small opening significantly reduces the useful life of the needle valve.

[0036] However, although the fixed current limiter 42 can keep the liquid flow rate controlled at a low level, it cannot regulate the flow rate of the liquid sample, which causes the flow rate of the liquid sample under different pressures to be unstable, resulting in poor consistency of subsequent sampling.

[0037] Therefore, in this embodiment, by connecting the variable current limiter 41 and the fixed current limiter 42 in series, the flow rate of the liquid sample supplied to the heating module 3 can be controllably adjusted, while the service life of the current limiter 4 can be improved.

[0038] In this embodiment, a flow meter 43 and a controller 44 are further added to the current limiting device 4. The flow meter 43 may be installed before or after the heating unit and is capable of detecting the flow rate in the pipeline in which the current limiting device 4 is installed. The controller 44 is communicatively connected to the flow meter 43 and the variable current limiter 41, and adjusts the opening of the variable current limiter 41 based on the flow rate detected by the flow meter 43. For example, a technician sets a predetermined flow rate in the controller 44, obtains the detection result of the flow meter 43 in real time or at predetermined intervals, compares the detection result of the flow meter 43 with the predetermined flow rate, and issues a control command to the variable current limiter 41 to decrease the opening if the detection result of the flow meter 43 exceeds the predetermined flow rate, and issues a control command to the variable current limiter 41 to increase the opening if the detection result of the flow meter 43 is below the predetermined flow rate.

[0039] In this embodiment, the needle valve and damper tube are combined to adjust the flow rate of the liquid sample, allowing the needle valve to adjust to a low liquid flow rate at a relatively large opening, thereby improving the service life of the needle valve, saving costs, and reducing the difficulty of customizing a needle valve for a smaller flow rate. Furthermore, the flow rate of the vaporized gas sample can be monitored by flow meter 43, and in conjunction with the control of variable current limiter 41 by controller 44, the flow rate of the gas sample delivered to gas chromatograph 200 via gas sample outlet 2 can be controlled with high precision.

[0040] In this embodiment, the flow rate is adjusted using the controller 44, but the above description is merely exemplary, and in other embodiments of the present application, the flow rate may be adjusted manually. Third embodiment

[0041] FIG. 3 is a structural schematic diagram of a preferred vaporizer according to an embodiment of the present invention. As shown in FIG. 3, the vaporizer 100 may further include a tracing tube 6. In some preferred embodiments, the tracing tube 6 is located at the inlet of a gas chromatograph 200. That is, the vaporizer 100 communicates with the gas chromatograph 200 via the tracing tube 6. Specifically, the tracing tube 6 has a gas sample outlet line 61, both ends of which are connected to the heating module 3 and the gas sample outlet 2, respectively. The vaporized gas sample is introduced into the gas chromatograph 200 through the tracing tube 6. This ensures that the gas sample passing through the heating module 3 passes through the tracing tube 6 before entering the gas chromatograph 200, preventing condensation of the vaporized sample and improving detection accuracy.

[0042] Furthermore, in some other preferred embodiments, the tracing tube 6 may be connected to the sample outlet of the gas chromatograph 200. Specifically, the vaporizer 100 may further include an exhaust port 7, and the tracing tube 6 may further have a return air flow path 62, one end of which is connected to the gas chromatograph 200 to receive the gas sample returned from the gas chromatograph 200, and the other end of which is connected to the exhaust port 7 via the flow meter 43. By introducing the gas sample at the outlet of the gas chromatograph 200 into the flow meter 43 via the tracing tube 6, a decrease in flow rate due to cooling of the gas sample can be avoided, and the reading of the flow meter 43 can accurately reflect the flow rate of the gas sample introduced into the gas chromatograph 200. Preferably, the flow meter 43 is a float-type flow meter 43, which can better reflect the flow rate of the gas sample from the gas chromatograph 200.

[0043] Preferably, inlet 1 includes liquid sample inlet 11 and gas sample inlet 12, and vaporizer 100 further includes two-way valve 8 and three-way valve 13. Two-way valve 8 is connected to exhaust port 7. One side of three-way valve 13 is connected to either liquid sample inlet 11 or gas sample inlet 12, and the other side is connected to both motorized shut-off valve 5 and two-way valve 8. Specifically, by switching three-way valve 13, it is possible to select whether to introduce a liquid sample for analysis through liquid sample inlet 11 or gas sample inlet 12, thereby enabling a single vaporizer 100 to perform pretreatment of both liquid and gas samples. Furthermore, the two-way valve is connected to exhaust port 7, allowing the pipeline from inlet 1 to exhaust port 7 to be purged after each analysis to prevent residue from the previous sample and improve detection accuracy.

[0044] Preferably, the vaporizer 100 may further include a filter 9 disposed between the three-way valve 13 and the motorized shutoff valve 5, and the filter 9 may be a metal mesh filter 9. The filter 9 filters out impurities such as solid particles in the liquid sample, thereby preventing clogging of the downstream current limiting device 4.

[0045] The injection device in this embodiment can be applied to a gas chromatograph 200, which can flash vaporize a liquid sample to obtain a gas sample, and control the gas sample at a constant flow rate to be continuously introduced into the gas chromatograph 200 for analysis, thereby achieving accurate and stable analysis of the sample in the gas chromatograph 200.

[0046] The above is merely a preferred embodiment of the present invention, and does not limit the present invention. Any modifications, equivalent replacements, and improvements made within the spirit and principle of the present invention shall fall within the scope of protection of the present invention. [Explanation of symbols]

[0047] 100 - vaporizer, 200 - gas chromatograph, 1 - inlet, 11 - liquid sample inlet, 12 - gas sample inlet, 13 - three-way valve, 2 - gas sample outlet, 3 - heating module, 4 - current limiter, 41 - variable current limiter, 42 - fixed current limiter, 43 - flow meter, 44 - controller, 5 - motorized shut-off valve, 6 - tracing tube, 61 - gas sample outlet line, 62 - return air flow path, 7 - exhaust port, 8 - two-way valve, 9 - filter.

Claims

1. It is applied to sample pretreatment for gas chromatography, An inlet; a gas sample outlet; a heating module communicating with both the inlet and the gas sample outlet, flash-vaporizing a liquid sample from the inlet into a gas sample and transporting the gas sample to the gas chromatograph via the gas sample outlet; The vaporizer further comprises a flow limiting device provided in a pipeline between the heating module and the injection port, the flow limiting device having an adjustable flow rate.

2. The current limiting device is A variable current limiter; a fixed current limiter connected in series with the variable current limiter, The vaporizer comprises: a flow meter for detecting a flow rate in the pipeline in which the current limiting device is provided; The vaporizer described in claim 1, further comprising a controller communicatively connected to the flow meter and the variable current limiter, respectively, and adjusting the opening degree of the variable current limiter based on the flow rate detected by the flow meter.

3. 3. The vaporizer according to claim 2, wherein the variable current limiter is a needle valve, and the fixed current limiter is a damper tube.

4. the vaporizer further comprises a tracing tube; The vaporizer of claim 2, wherein the vaporizer is connected to the gas chromatograph via the tracing tube, and the tracing tube has a gas sample outlet line whose two ends are connected to the heating module and the gas sample outlet, respectively.

5. further including an exhaust outlet; The vaporizer of claim 4, wherein the tracing tube further has a return air flow path, one end of which is connected to the gas chromatograph for receiving the gas sample returned from the gas chromatograph, and the other end of which is connected to the exhaust port via the flow meter.

6. 6. The vaporizer according to claim 5, wherein the flow meter is a float-type flow meter.

7. The vaporizer of claim 5 , further comprising an electrically operated shutoff valve disposed between the current limiting device and the inlet and communicatively connected to the controller.

8. the inlet includes a liquid sample inlet and a gas sample inlet; The vaporizer comprises: a two-way valve communicating with the exhaust port; The vaporizer of claim 7, further comprising a three-way valve, one side of which is selectively connected to the liquid sample inlet or the gas sample inlet, and the other side of which is connected to both the motorized shut-off valve and the two-way valve.

9. The vaporizer according to claim 8 , further comprising a filter disposed between the three-way valve and the electrically operated shutoff valve.

10. A gas chromatograph comprising the vaporizer according to any one of claims 1 to 9.

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