Gas chromatograph shunting outlet filtering device

Abstract

The utility model discloses a split-flow outlet filtering device of a gas chromatograph, and belongs to the technical field of analysis and test application. Comprising a long-barrel-shaped outer shell, an air inlet connector and an air outlet connector, the air inlet connector and the air outlet connector are arranged at the two ends of the outer shell, a long-barrel-shaped filter element shell is arranged in the outer shell in a sleeved mode, and a first filter layer, a second filter layer, a third filter layer and a filter covering film are sequentially arranged in the filter element shell from the air inlet connector to the air outlet connector. And sealing rings are arranged between the first filtering layer and the air inlet joint and between the filtering covering film and the air outlet joint. The failure rate of the electronic pressure controller is greatly reduced, and the stable service life of an instrument is prolonged.

Description

Technical Field

[0001] The utility model relates to a filtering device, in particular to a split outlet filtering device for a gas chromatograph. Background Technique

[0002] In split injection of a gas capillary column chromatograph, a sample with a relatively large volume is first injected into the vaporization chamber of the gas capillary column chromatograph. After the sample is vaporized, it is uniformly mixed with the carrier gas. Through the splitter, the sample is split into two parts with a large difference in flow rate. The part with a smaller flow rate enters the capillary column, and the part with a larger flow rate is vented. A splitter is a device that divides a gas or liquid into several parts according to a certain ratio, allowing a small part of the sample to enter the chromatographic column to prevent column overloading while most of it is vented.

[0003] The split outlet filtering device is an important component that affects the electronic pressure controller of the gas chromatograph. The sample split from the vaporization chamber of the gas capillary column chromatograph flows through the filtering device to the electronic pressure controller. Generally, the split ratio (usually refers to the ratio of the carrier gas flow rate entering the capillary column to the carrier gas flow rate of the vent) is set in the range of 1:50 to 1:200. Therefore, at least 98% of the sample will flow into the electronic pressure controller from the split outlet. Some high-boiling-point or dirty samples are vaporized at high temperature in the vaporization chamber, but the sample temperature drops and condenses into a solid after splitting, and it is extremely easy to flow into the electronic pressure controller along with the carrier gas, causing unstable pressure or a straight rise in the instrument. The filtering device can filter the sample and protect the gas chromatograph.

[0004] As Figure 1 shown, the filtering process of the existing split outlet filtering device is: split outlet gas → inlet joint 1 → quartz fiber filtering layer 3 → outlet joint 4. The original gas chromatograph split filtering device has a stainless steel shell 2, and the internal filler is a quartz fiber filtering layer 3. It can filter impurities with a diameter of 10um, but cannot filter hydrocarbons, water-containing substances, and finer impurities, and is prone to blockage. At the same time, the filtering effect of the filtering device is poor, and large particles in the sample contaminate the electronic control system of the gas chromatograph, resulting in unstable pressure or a straight rise at the split outlet, unable to provide a constant flow rate, and the system cannot be ready, seriously affecting the accuracy of analysis.

[0005] Therefore, it is necessary to transform the split outlet of the gas chromatograph, change the original single quartz fiber cotton split outlet filter to a multi-stage multi-functional split outlet filter, and try to reduce the pollution and damage to the electronic pressure controller. Content of the Utility Model

[0006] The purpose of the utility model is to solve the problems of easy blockage and poor filtering effect of the filtering device in the prior art, and to propose a split outlet filtering device for a gas chromatograph.

[0007] In order to achieve the above purpose, the utility model adopts the following technical scheme:

[0008] A split outlet filtering device for a gas chromatograph, comprising a long cylindrical outer casing and an inlet connector and an outlet connector provided at both ends of the outer casing. A long cylindrical filter element casing is sleeved inside the outer casing. A first filter layer, a second filter layer, a third filter layer and a filter film are sequentially arranged in the filter element casing from the inlet connector to the outlet connector. Sealing rings are provided between the first filter layer and the inlet connector and between the filter film and the outlet connector.

[0009] Further, the materials of the outer casing and the filter element casing are transparent PC, the material of the first filter layer is quartz fiber, the material of the second filter layer is activated carbon, the material of the third filter layer is discoloring silica gel, and the filter film is a PTFE film.

[0010] Further, the length of the outer casing is 18 - 20 cm, the length of the filter element casing is 15 - 18 cm, the filling length of the quartz fiber is 3 - 4 cm, the filling length of the activated carbon is 6 - 8 cm, the filling length of the discoloring silica gel is 5 - 6 cm, and the thickness of the PTFE film is 0.1 - 0.3 cm.

[0011] Further, the filtration accuracy of the first filter layer is not greater than 1μm, and the filtration accuracy of the filter film is not greater than 0.1μm.

[0012] Compared with the prior art, the present utility model provides a split outlet filtering device for a gas chromatograph, which has the following beneficial effects:

[0013] (1) Purchasing filter pipelines, connectors and filter fillers costs a total of 60 yuan; the internal technical personnel of the laboratory jointly transformed it, and no maintenance cost was generated. The total investment is 60 yuan. Calculated by the price of a single electronic pressure controller (EPC) for a gas chromatograph, which is 13,000 yuan per unit, the saved funds are: 13,000 - 60 = 12,940 yuan.

[0014] (2) By transforming the split outlet of the gas chromatograph and installing a filtering device, the failure rate of the electronic pressure controller is greatly reduced, and the stable use period of the instrument is extended. The re - optimization of resources and the sustainability of analysis are realized, and the repeatability of the analysis results is optimized.

[0015] (3) The split outlet filtering device of the gas chromatograph of the present utility model has a low cost. It is externally fixed at the split outlet of the instrument and has a small requirement for the operating space. Using a transparent outer casing tube and an inner filter element tube, the performance state of the filter layer can be visually observed. At the same time, the filter inner core is replaced regularly, and almost no failure phenomenon of the electronic pressure controller caused by sample split pollution will occur, and it has excellent stability during the analysis of the chromatograph. Description of the Drawings

[0016] Figure 1Schematic diagram of the structure of the split outlet filtration device of the gas chromatograph before transformation.

[0017] Figure 2 Schematic diagram of the structure of the present utility model;

[0018] Figure 3 Exploded view of the structure of the present utility model;

[0019] In the figure: 1. Inlet joint, 2. Outer shell, 3. Quartz fiber filter layer, 4. Outlet joint, 5. Filter element housing, 6. First filter layer, 7. Second filter layer, 8. Third filter layer, 9. Filter film, 10. O-ring seal, 11. O-ring seal. Specific embodiments

[0020] Next, the technical solutions in the embodiments of the present utility model will be clearly and completely described in conjunction with the accompanying drawings of the present utility model. Obviously, the described embodiments are only a part of the embodiments of the present utility model, rather than all of the embodiments.

[0021] Embodiment 1

[0022] A split outlet filtration device for a gas chromatograph, referring to Figure 2 and Figure 3 , includes a long cylindrical outer shell 2 and an inlet joint 1 and an outlet joint 4 provided at both ends of the outer shell 2. A long cylindrical filter element housing 5 is sleeved inside the outer shell 2. A first filter layer 6, a second filter layer 7, a third filter layer 8 and a filter film 9 are sequentially provided in the filter element housing 5 from the inlet joint to the outlet joint. An O-ring seal 10 is provided between the first filter layer 6 and the inlet joint 1, and an O-ring seal 11 is provided between the filter film 9 and the outlet joint 4.

[0023] Among them, the materials of the outer shell 2 and the filter element housing 5 are transparent PC, the material of the first filter layer 6 is quartz fiber, the material of the second filter layer 7 is activated carbon, the material of the third filter layer 8 is discolored silica gel, and the filter film 9 is a PTFE film.

[0024] The length of the outer shell 2 is 18 - 20 cm, the length of the filter element housing 5 is 15 - 18 cm, the filling length of the quartz fiber is 3 - 4 cm, the filling length of the activated carbon is 6 - 8 cm, the filling length of the discolored silica gel is 5 - 6 cm, and the thickness of the PTFE film is 0.1 - 0.3 cm.

[0025] The filtration accuracy of the first filter layer 6 is not greater than 1 μm, and the filtration accuracy of the filter film 9 is not greater than 0.1 μm.

[0026] This utility model replaces the stainless - steel shell with a hard - transparent polycarbonate (PC) round - tube shell 2, which makes it easier to observe the internal filter element. The length is increased from 12 cm to 18 cm; a hard - transparent polycarbonate (PC) round - tube 5 for the filter - element housing is added, with a length of 15 cm, to prevent the shell from deforming due to high carrier - gas pressure; four filter layers are sequentially filled in the filter - element housing 5, in the order of quartz fiber 6 → activated carbon 7 → discolored silica gel 8 → polytetrafluoroethylene (PTFE) 9. The widths of the filter layers are 3 - 4 cm for quartz fiber, 6 - 8 cm for activated carbon, 5 - 6 cm for discolored silica gel, and 0.2 cm for PTFE membrane. They respectively adsorb large - particle impurities, volatile organic compounds, water, and impurities smaller than 1 μm in the shunt - outlet sample. It solves the problems of dirty and water - containing shunt - outlet samples polluting or damaging the electronic pressure controller. When the gas chromatograph is injected 50 times or when any filter layer fails, the filter core is replaced to prevent the filter from saturation failure and protect the electronic pressure controller. The inlet joint 1 and the outlet joint 4 of the filter are sealed with O - type seals 10 and 11 at both ends to the filter core, preventing gas leakage from the filtering device and ensuring normal pressure of the chromatograph.

[0027] The inlet joint 1, the outlet joint 4, and the outer shell 2 of the shunt - outlet filtering device of the gas chromatograph form a closed cavity, and a filter - element housing 5 is placed in the cavity.

[0028] The inlet joint 1 is used to connect the shunt - outlet pipeline of the gas chromatograph. One end of the outer shell 2 is thread - connected to the inlet joint 1 and is sealed with an O - type seal 10.

[0029] The outlet joint 4 is used to connect the electronic pressure controller (EPC) of the gas chromatograph. The other end of the outer shell 2 is thread - connected to the outlet joint 8 and is sealed with an O - type seal 11.

[0030] The first filter layer 6, the second filter layer 7, the third filter layer 8, and the fourth filter film 9 are filled in the filter - element housing 5. The first filter layer 6 is made of quartz fiber with a filtration accuracy of 1 μm; the second filter layer 7 is made of activated carbon to adsorb organic substances; the third filter layer 8 is made of discolored silica gel to adsorb water; the fourth filter film 9 is made of polytetrafluoroethylene (PTFE) with a filtration accuracy of 0.1 μm.

[0031] The working steps of the device are as follows: the shunt - outlet sample of the gas chromatograph enters the filter - element housing 5 through the inlet joint 1. The gas first passes through the first filter layer 6 for filtration, then through the second filter layer 7 for filtration, then through the third filter layer 8 for filtration, and finally through the fourth filter film 9 for filtration. The filtered gas is discharged from the outlet joint 4 and flows into the electronic pressure controller (EPC).

[0032] The above are only the preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A gas chromatograph split outlet filtering device, comprising a long cylindrical outer shell and an air inlet connector and an air outlet connector arranged at both ends of the outer shell, characterized in that: A long cylindrical filter element housing is sleeved in the outer shell, and a first filter layer, a second filter layer, a third filter layer and a filter membrane are arranged in sequence from the air inlet joint to the air outlet joint in the filter element housing, and sealing rings are arranged between the first filter layer and the air inlet joint and between the filter membrane and the air outlet joint.

2. The gas chromatograph split flow outlet filtering device according to claim 1, characterized in that: The outer shell and the filter element shell are made of transparent PC, the first filter layer is made of quartz fiber, the second filter layer is made of activated carbon, the third filter layer is made of color-changing silica gel, and the filter membrane is a PTFE membrane.

3. The gas chromatograph split outlet filtering device according to claim 2, characterized in that: The length of the outer shell is 18-20 cm, the length of the filter element shell is 15-18 cm, the filling length of the quartz fiber is 3-4 cm, the filling length of the activated carbon is 6-8 cm, the filling length of the color-changing silica gel is 5-6 cm, and the thickness of the PTFE membrane is 0.1-0.3 cm.

4. The gas chromatograph split outlet filtering device according to claim 1, characterized in that: The filtering accuracy of the first filter layer is not greater than 1 μm, and the filtering accuracy of the filter membrane is not greater than 0.1 μm.

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