Flash evaporator and gas chromatograph

Abstract

The utility model relates to the technical field of analysis, and provides a flash evaporator and a gas chromatograph with the flash evaporator, which can avoid pressure building of a vaporized sample and enable the sample to be completely vaporized by a heating module. The flash evaporator is applied to sample pretreatment of a gas chromatograph and comprises a sample inlet, a gas sample outlet, a heating module and a flow limiting device. The heating module is communicated with the sample inlet and the gas sample outlet, a liquid sample entering from the sample inlet is flashed into a gas sample, and the gas sample is conveyed to the gas chromatograph through the gas sample outlet. Particularly, the flash evaporator further comprises a flow limiting device, and the flow limiting device is arranged in a pipeline between the heating module and the sample inlet.

Description

Technical Field

[0001] The utility model relates to the technical field of analysis, in particular to a flash evaporator and a gas chromatograph with the flash evaporator. Background Art

[0002] In some test detection and analysis scenarios, such as when analyzing samples with a gas chromatograph, it is often necessary to pre-process the liquid sample, vaporize the liquid sample into a gas sample, and then take the gas sample for detection and analysis.

[0003] The commonly used vaporization method at present is to heat the liquid sample through a heating module for flash vaporization, and use a needle valve or solenoid valve to adjust the gas flow after vaporization. However, since the volume of the liquid will expand about 1000 times after vaporization, a very small amount of liquid sample will produce a very large volume of gas. Therefore, the sample gas after vaporization is limited in flow, which will lead to pressure buildup. The gas pressure will be higher than the atmospheric pressure, which can easily cause the high-boiling point gas components that have been vaporized to condense. In order to ensure the vaporization of the high-boiling point components, a higher vaporization temperature is required than at atmospheric pressure. At this time, the material components that are sensitive to temperature may decompose and denature. Utility Model Content

[0004] In view of the above problems, the utility model provides a flash evaporator and a gas chromatograph having the flash evaporator, which can avoid pressure buildup of the sample after vaporization and enable the sample to be completely vaporized by the heating module.

[0005] The present invention provides, on one hand, a flash evaporator for use in sample pretreatment for a gas chromatograph. The flash evaporator comprises 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-evaporates a liquid sample entering the inlet into a gas sample, which is then delivered to the gas chromatograph via the gas sample outlet. Specifically, the flash evaporator further comprises a flow limiting device disposed in a pipeline between the heating module and the inlet, and the flow rate limited by the flow limiting device is adjustable.

[0006] According to the technical solution of the present invention, a liquid sample enters the flash evaporator through the sample inlet, is limited to a smaller flow rate by a flow limiting device, and then enters the heating module for heating and flash vaporization, obtaining a vaporized gas sample. The gas sample is then transported to the gas chromatograph via the gas sample outlet. By controlling the flow limiting device, the flow rate of the liquid sample entering the heating module can be controlled so that the liquid sample entering the heating module can be completely vaporized. Moreover, since the flow limiting device is located before the heating module and has an adjustable flow rate, the flow rate of the gas sample can be adjusted without causing pressure buildup in the vaporized sample.

[0007] As a preferred technical solution, the flow limiting device includes an adjustable flow restrictor, a fixed flow restrictor, a flow meter, and a controller. The fixed flow restrictor and the adjustable flow restrictor are connected in series. The flow meter is used to detect the flow rate in the pipeline in which the flow limiting device is installed. The controller is in communication with the flow meter and the adjustable flow restrictor, and adjusts the opening of the adjustable flow restrictor based on the flow rate detected by the flow meter.

[0008] According to the preferred technical solution, since liquid standards are often very expensive, and since the volume of the liquid sample will expand after vaporization, the amount of liquid sample required for actual analysis is very small, so the liquid flow rate that needs to be controlled is at a very low level. The current adjustable restrictor is difficult to achieve at a very low flow rate. Even if it can be achieved, the service life of the adjustable restrictor will be shortened. Although the fixed restrictor can continuously control the liquid flow rate at a lower level, the flow rate of the liquid sample cannot be adjusted, resulting in inconsistent flow rates of liquid samples of different pressures, affecting the consistency of subsequent sampling. Therefore, by connecting the adjustable restrictor and the fixed restrictor in series, the flow rate of the liquid sample entering the heating module can be controllably adjusted, and the service life of the current limiting device can be improved.

[0009] It is worth mentioning that the flow rate of the vaporized gas sample can be observed through the flow meter, and the flow rate of the gas sample delivered to the gas chromatograph through the gas sample outlet can be accurately controlled by coordinating the controller to control the adjustable restrictor.

[0010] As a preferred technical solution, the adjustable flow limiter is a needle valve, and the fixed flow limiter is a damping tube.

[0011] According to this preferred technical solution, the flow rate of the liquid sample is adjusted by a combination of a needle valve and a damping tube, so that the needle valve can be adjusted to a very small liquid flow rate at a larger opening, thereby increasing the service life of the needle valve, saving costs or reducing the difficulty of customizing a needle valve with a smaller flow specification.

[0012] As an optimal technical solution, the flash evaporator also includes a heating pipe, which is connected to the gas chromatograph via the heating pipe. The heating pipe has a gas sample outflow pipeline, and the two ends of the gas sample outflow pipeline are respectively connected to the heating module and the gas sample outlet.

[0013] According to this preferred technical solution, the gas sample passing through the heating module passes through the heating pipe and then enters the gas chromatograph, thereby further ensuring that the vaporized sample no longer condenses, thereby improving the accuracy of detection.

[0014] As an optimal technical solution, the flash evaporator also includes an exhaust port, and the heating pipe also has a return gas flow path, one end of which is used to connect with the sample outlet of the gas chromatograph to receive the gas sample returned from the gas chromatograph, and the other end is connected with 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 passed through a heating pipe and then into the flow meter, which can avoid the dead volume of the flow meter and the influence of trace leakage that is difficult to avoid, thereby reducing the purge time of each injection.

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

[0017] As a preferred technical solution, the flash evaporator further includes an electric stop valve, which is arranged between the flow limiting device and the sample inlet and is communicatively connected to the controller.

[0018] According to this preferred technical solution, the electric stop valve is controlled by the controller to quickly start / stop the injection of the liquid sample without manual operation, saving manpower and being convenient and fast.

[0019] As a preferred technical solution, the sample inlet includes a liquid sample inlet and a gas sample inlet, and the flash evaporator also includes a two-way valve and a three-way valve. The two-way valve is connected to the exhaust port, and one side of the three-way valve is connected to either the liquid sample inlet or the gas sample inlet, while the other side is connected to both the electric shut-off valve and the two-way valve.

[0020] According to this preferred technical solution, a three-way valve can be used to switch between liquid and gas samples, allowing both liquid and gas sample injection and analysis to be completed using a single flash evaporator. Furthermore, the two-way valve is connected to the exhaust port, facilitating purge of the line from the injection port to the exhaust port to prevent carryover of the previous sample.

[0021] As a preferred technical solution, the flash evaporator further includes a filter, which is arranged between the three-way valve and the electric stop valve.

[0022] According to this preferred technical solution, the filter can filter out some solid particle impurities in the liquid sample to avoid clogging the downstream flow limiting device.

[0023] A second aspect of the present invention provides a gas chromatograph comprising a flash evaporator as in any of the above technical solutions. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a structural schematic diagram of a flash evaporator provided in an embodiment of the present utility model.

[0025] Figure 2 It is a structural schematic diagram of a preferred current limiting device provided in an embodiment of the present utility model.

[0026] Figure 3 It is a structural schematic diagram of a preferred flash evaporator provided by an embodiment of the present utility model.

[0027] Figure markings: 100-flash evaporator; 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-flow limiting device; 41-adjustable flow restrictor; 42-fixed flow restrictor; 43-flow meter; 44-controller; 5-electric stop valve; 6-heating pipe; 61-gas sample outflow pipeline; 62-return flow path; 7-exhaust port; 8-two-way valve; 9-filter. DETAILED DESCRIPTION

[0028] The following will be combined with the accompanying drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] First embodiment

[0030] Figure 1 This is a schematic diagram of the structure of a flash evaporator provided by the embodiment of the present utility model. Figure 1 As shown, the flash evaporator 100 includes a sample inlet 1 , a gas sample outlet 2 , a heating module 3 and a flow limiting device 4 .

[0031] Among them, the sampling port 1 at least includes a liquid sample sampling port 1, and the technician can inject the liquid sample into the flash evaporator 100 through the liquid sample sampling port 1, or the sampling port 1 can also be used in conjunction with a quantitative extraction device such as a volumetric pump, so as to automatically complete quantitative sampling and better control the volume of the injected liquid sample.

[0032] The heating module 3 is disposed on the downstream pipeline of the injection port 1. The heating module 3 can be an electric heater or a heat exchanger, which is not limited here. Generally speaking, the heating module 3 needs to be able to wrap and heat a relatively long pipeline. For example, the heating module 3 can be an electric heating box. The pipeline downstream of the injection port is coiled inside the electric heating box. The liquid sample entering from the injection port 1 is rapidly heated and vaporized in the heating box along with the pipeline. The vaporized gas sample finally flows out of the outlet of the heating box and is then transported to the gas chromatograph 200 through the gas sample outlet 2.

[0033] In particular, the flash evaporator 100 further includes a flow limiting device 4, which is disposed in the pipeline between the heating module 3 and the sample inlet 1 and limits the flow rate to be adjustable. The flow limiting device 4 can be any device capable of limiting the flow rate of the liquid sample to a specified value or value range, and the value or value range is adjustable. The value or value range can be set according to the power of the heating module 3 and configured to utilize the heating module 3 to vaporize the entire liquid sample while avoiding a flow value or value range that inhibits detection efficiency.

[0034] In some preferred embodiments, the flash evaporator 100 may further include an electric stop valve 5 (see Figure 3 ), the electric stop valve 5 is arranged between the flow limiting device 4 and the sampling port 1, and is communicated with the controller 44. The electric stop valve 5 is controlled by the controller 44 to quickly start / stop the injection of the liquid sample without manual operation, saving manpower and being convenient and fast.

[0035] Specifically, the liquid sample enters the flash evaporator 100 from the inlet 1, is limited to a smaller flow rate by the flow limiting device 4, and then enters the heating module 3 for heating and flash vaporization to obtain a vaporized gas sample. The gas sample is then transported to the gas chromatograph 200 through the gas sample outlet 2.

[0036] In this embodiment, the flow rate of the liquid sample entering the heating module 3 is controlled by the flow limiting device 4, so that the liquid sample entering the heating module 3 can be completely vaporized. Moreover, since the flow limiting device 4 is before the heating module 3, it can achieve flow regulation of the gas sample without causing pressure buildup in the vaporized sample.

[0037] Second embodiment

[0038] Figure 2 This is a schematic diagram of the structure of a preferred current limiting device provided by the embodiment of the present utility model. Figure 2 As shown, compared with the first embodiment, this embodiment provides a more detailed structure of the flow limiting device 4 , which includes an adjustable flow limiter 41 , a fixed flow limiter 42 , a flow meter 43 and a controller 44 .

[0039] Among them, the fixed flow restrictor 42 and the adjustable flow restrictor 41 are arranged in series between the sample inlet 1 and the heating part. The fixed flow restrictor 42 refers to a flow restrictor that can fixedly reduce the liquid flow but cannot be adjusted, such as a pressure drop flow restrictor such as a damping tube; the adjustable flow restrictor 41 refers to a flow restrictor that can regulate the flow rate by means of valve opening, such as an opening-controlled flow restrictor such as a needle valve. It is worth mentioning that since the adjustable flow restrictor 41 such as a needle valve controls the flow rate of the liquid sample by controlling the opening, an excessively small opening may cause the upstream pressure of the valve to increase, and even reduce the service life of the valve or damage it.

[0040] However, since liquid standards are often very expensive and the volume of liquid samples expands after vaporization, the amount of liquid sample required for actual analysis is very small, so the liquid flow rate needs to be controlled at a very low level (in some embodiments, the flow rate of the liquid sample needs to be controlled below 0.2 mL / min).

[0041] Based on the flow limiting principle of the adjustable flow limiter 41, it is difficult for the current adjustable flow limiter 41 to reach a very low flow rate. Even if it can be reached, the adjustable flow limiter 41 needs to be maintained at a very small opening. For example, for a needle valve, the needle valve with the smallest flow control on the market can only barely achieve this within an opening of only 1 circle, but such a small opening will seriously affect the service life of the needle valve.

[0042] Although the fixed flow restrictor 42 can continuously control the liquid flow at a low level, it cannot adjust the flow of the liquid sample, resulting in inconsistent flow rates of liquid samples with different pressures, affecting the consistency of subsequent sampling.

[0043] Therefore, in this embodiment, by connecting the adjustable flow restrictor 41 and the fixed flow restrictor 42 in series, the flow rate of the liquid sample entering the heating module 3 can be controllably adjusted, and the service life of the flow restrictor 4 can be improved.

[0044] In addition, in this embodiment, a flow meter 43 and a controller 44 are also added to the flow limiting device 4. The flow meter 43 can be arranged before or after the heating part. The flow meter 43 can detect the flow in the pipeline where the flow limiting device 4 is arranged. The controller 44 is respectively connected to the flow meter 43 and the adjustable flow restrictor 41 for communication, and adjusts the opening of the adjustable flow restrictor 41 according to the flow detected by the flow meter 43. For example, a technician can set a predetermined flow rate for the controller 44, and obtain the detection result of the flow meter 43 in real time or at intervals, and compare the detection result of the flow meter 43 with the predetermined flow rate. If the detection result of the flow meter 43 is greater than the predetermined flow rate, a control instruction to reduce the opening of the adjustable flow restrictor 41 is issued. If the detection result of the flow meter 43 is less than the predetermined flow rate, a control instruction to increase the opening of the adjustable flow restrictor 41 is issued.

[0045] In this embodiment, the liquid sample flow rate is regulated by combining a needle valve and a damping tube. This allows the needle valve to be adjusted to a very low liquid flow rate at a wide opening, thereby extending the needle valve's service life, saving costs, and reducing the difficulty of customizing a needle valve with a smaller flow specification. Furthermore, the flow rate of the vaporized gas sample can be monitored by flow meter 43. This, in conjunction with controller 44 controlling adjustable restrictor 41, allows for accurate control of the gas sample flow rate delivered to gas chromatograph 200 via gas sample outlet 2.

[0046] It should be noted that, although the controller 44 is used to adjust the flow in this embodiment, the above description is only exemplary. In other embodiments of the present application, flow adjustment can also be completed by manual adjustment.

[0047] Third embodiment

[0048] Figure 3 This is a schematic diagram of the structure of a preferred flash evaporator provided by the embodiment of the present invention. Figure 3 As shown, the flash evaporator 100 may further include a heat tracing pipe 6. In some preferred embodiments, the heat tracing pipe 6 is disposed at the inlet of the gas chromatograph 200, i.e., the flash evaporator 100 is connected to the gas chromatograph 200 via the heat tracing pipe 6. Specifically, the heat tracing pipe 6 has a gas sample outflow pipeline 61, the two ends of which are respectively connected to the heating module 3 and the gas sample outlet 2. The vaporized gas sample is passed into the gas chromatograph 200 through the heat tracing pipe 6, which ensures that the gas sample passing through the heating module 3 passes through the heat tracing pipe 6 before entering the gas chromatograph 200, thereby further ensuring that the vaporized sample does not condense, thereby improving the accuracy of detection.

[0049] Furthermore, in other preferred embodiments, the heat tracing pipe 6 can also be connected to the sample outlet of the gas chromatograph 200. Specifically, the flash evaporator 100 can also include an exhaust port 7. The heat tracing pipe 6 also has a return gas flow path 62. One end of the return gas flow path 62 is used to communicate with the gas chromatograph 200 to receive the gas sample returned from the gas chromatograph 200, and the other end is connected to the exhaust port 7 via a flow meter 43. The gas sample at the outlet of the gas chromatograph 200 is passed through the heat tracing pipe 6 and then into the flow meter 43. This can prevent the gas sample from cooling and causing a decrease in flow rate, so that the reading of the flow meter 43 can truly reflect the flow rate of the gas sample entering the gas chromatograph 200. Preferably, the flow meter 43 is a float flow meter 43, which can better reflect the flow rate of the gas sample flowing out of the gas chromatograph 200.

[0050] Wherein, preferably, the injection port 1 includes a liquid sample inlet 11 and a gas sample inlet 12, and the flash evaporator 100 also includes a two-way valve 8 and a three-way valve 13. Wherein, the two-way valve 8 is connected to the exhaust port 7, and one side of the three-way valve 13 is connected to the liquid sample inlet 11 or the gas sample inlet 12, and the other side is connected to the electric stop valve 5 and the two-way valve 8. Specifically, by switching the three-way valve 13, it is possible to choose to access the liquid sample from the liquid sample inlet 11, or to access the gas sample from the gas sample inlet 12 for analysis, so that the pre-treatment of the liquid sample and the gas sample can be completed together by a flash evaporator 100. In addition, the two-way valve is connected to the exhaust port 7. After one analysis is completed, the pipeline from the injection port 1 to the exhaust port 7 can be purged to prevent the residue of the previous sample and improve the accuracy of the detection.

[0051] Among them, preferably, the flash evaporator 100 can also include a filter 9, which is arranged between the three-way valve 13 and the electric stop valve 5. The filter 9 can be a metal mesh filter 9. The filter 9 can filter out some solid particle impurities in the liquid sample to avoid clogging the downstream flow limiting device 4.

[0052] The sampling device in this embodiment can be used in the gas chromatograph 200, so that the liquid sample can be flash vaporized to obtain a gas sample, and the gas sample at a certain flow rate can be controlled to continuously enter the gas chromatograph 200 for analysis, which can ensure that the gas chromatograph 200 can perform more accurate and stable analysis of the sample.

[0053] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent replacements and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A flash evaporator, used for sample pretreatment of a gas chromatograph, comprising: Inlet; Gas sample outlet; A heating module is connected to the sample inlet and the gas sample outlet, and flashes the liquid sample entering the sample inlet into a gas sample, and transmits the gas sample to the gas chromatograph through the gas sample outlet, characterized in that the flash evaporator further includes: A flow limiting device is provided in the pipeline between the heating module and the injection port, and the flow limit of the flow limiting device is adjustable.

2. The flash evaporator according to claim 1, wherein The current limiting device comprises: Adjustable current restrictor; A fixed flow restrictor is connected in series with the adjustable flow restrictor, and the flash evaporator further includes: a flow meter for detecting the flow in the pipeline provided with the flow limiting device; The controller is in communication with the flow meter and the adjustable flow restrictor respectively, and adjusts the opening of the adjustable flow restrictor according to the flow detected by the flow meter.

3. The flash evaporator according to claim 2, wherein The adjustable flow restrictor is a needle valve, and the fixed flow restrictor is a damping tube.

4. The flash evaporator according to claim 2, wherein Also includes: A heating pipe, the flash evaporator is connected to the gas chromatograph via the heating pipe, the heating pipe has a gas sample outflow pipeline, and the two ends of the gas sample outflow pipeline are respectively connected to the heating module and the gas sample outlet.

5. The flash evaporator according to claim 4, characterized in that Also includes: The exhaust port, the heating pipe also has a return gas flow path, one end of the return gas flow path is used to communicate with the gas chromatograph to receive the gas sample returned from the gas chromatograph, and the other end is connected to the exhaust port via the flow meter.

6. The flash evaporator according to claim 5, characterized in that The flow meter is a float flow meter.

7. The flash evaporator according to claim 5, characterized in that Also includes: The electric stop valve is arranged between the flow limiting device and the sampling port and is communicatively connected with the controller.

8. The flash evaporator according to claim 7, wherein The sample inlet includes a liquid sample inlet and a gas sample inlet, and the flash evaporator further includes: a two-way valve connected to the exhaust port; The three-way valve has one side connected to either the liquid sample inlet or the gas sample inlet, and the other side connected to both the electric stop valve and the two-way valve.

9. The flash evaporator according to claim 8, wherein Also includes: A filter is arranged between the three-way valve and the electric stop valve.

10. A gas chromatograph, characterized in that: A flash evaporator according to any one of claims 1 to 9 is provided.

Images