CN-122017100-A - Explosion-proof discharge helium ionization detection system and preparation method thereof

CN122017100ACN 122017100 ACN122017100 ACN 122017100ACN-122017100-A

Abstract

The invention belongs to the technical field of gas chromatographic analysis, and particularly relates to an explosion-proof discharge helium ionization detection system and a preparation method thereof. The detector comprises a detector main body, a discharge chamber, an ionization chamber, a double-electrode feed-through flange upper cover, a current sensor, an explosion-proof shell, a sealing hole and a coaxial cable, wherein the discharge chamber and the ionization chamber are coaxially arranged at the inner sides of the upper end and the lower end of the detector main body respectively, the discharge chamber and the ionization chamber are communicated through needle-shaped small holes, the double-electrode feed-through flange upper cover is fixed at the upper end of the discharge chamber in a sealing mode, the double electrodes in the double-electrode feed-through flange upper cover coaxially extend into the discharge chamber and are respectively connected with the positive electrode and the negative electrode of a high-voltage power supply, the current sensor is fixed at the lower end of the ionization chamber in a sealing mode, and the current sensor extends into the ionization chamber through a parallel polar plate and is used for acquiring ion current, and the explosion-proof shell covers the detector main body and is provided with the sealing hole for a coaxial cable to pass through. The invention reduces the influence of the change of the sectional area of the gas path on the flow speed of the carrier gas and the pressure drop of the gas path, thereby improving the detection performance.

Inventors

GUAN LEI
GUO LIZHEN
MIAO YINXIAO
BU FANG
WANG TIEBIN
CUI CHUNMEI
LIN AIJING
WANG XIN

Assignees

北京航天计量测试技术研究所

Dates

Publication Date: 20260512
Application Date: 20251126

Claims (10)

1. An explosion-proof discharge helium ionization detection system, comprising: The detector comprises a detector main body (1), wherein the inner sides of the upper end and the lower end of the detector main body are respectively and coaxially provided with a discharge chamber (2) and an ionization chamber (3), and the discharge chamber (2) and the ionization chamber (3) are communicated through needle-shaped small holes; the double-electrode feed-through flange upper cover (4) is hermetically fixed at the upper end of the discharge chamber (2), and double electrodes in the double-electrode feed-through flange upper cover (4) coaxially extend into the discharge chamber (2) and are respectively connected with the positive electrode and the negative electrode of the power supply; The current sensor (5) is hermetically fixed at the lower end of the ionization chamber (3), and extends into the ionization chamber (3) through a parallel polar plate to acquire ion current, and a weak current acquisition module is used for collecting weak signals; And an explosion-proof housing (11) which covers the detector main body (1) and is provided with a threaded through hole and a straight slot hole for the cable and the stainless steel pipe to pass through.
2. The explosion-proof type discharge helium ionization detection system according to claim 1, further comprising: a first air inlet hole (6) positioned at the side of the discharge chamber (2), and helium carrier gas is introduced from the first air inlet hole (6); a second air inlet hole (7) positioned at the side of the ionization chamber (3), and sample gas is introduced from the second air inlet hole (7); and an exhaust hole (8) located at a side of the ionization chamber (3), and discharging the mixed ionized gas from the exhaust hole (8).
3. The explosion-proof type discharge helium ionization detection system according to claim 2, wherein the connection sides of the discharge chamber (2), the ionization chamber (3) and the needle-shaped small hole are contracted and reduced towards the needle-shaped small hole and are conical, namely, the needle-shaped small hole is a converging vertex of two funnels, and the discharge chamber (2), the ionization chamber (3) and the needle-shaped small hole are positioned on the same axis.
4. An explosion-proof type discharge helium ionization detection system according to claim 3, wherein the conical taper angle of the detector main body (1) is 135 °.
5. The explosion-proof type discharge helium ionization detection system according to claim 1, wherein the diameter of the needle-shaped small hole of the detector main body (1) is larger than the height of the needle-shaped small hole.
6. The explosion-proof type discharge helium ionization detection system according to claim 1, wherein the detector main body (1) is a cylindrical body with a side being milled flat, and the discharge chamber (2) and the ionization chamber (3) are generally cylindrical cavities.
7. The explosion-proof discharge helium ionization detection system according to claim 1, wherein the electrode of the double-electrode feed-through flange upper cover (4) comprises a metal nickel rod penetrating out of a 99 ceramic hollow column and sleeved at the tail end with a metal end cap, the volume of the ionization chamber (3) is not more than 500 microliters, and the volume of the discharge chamber (2) is 5-10 times of the volume of the ionization chamber (3).
8. The explosion-proof type discharge helium ionization detection system according to claim 7, wherein the lower end of a double electrode column of the double electrode feed-through flange upper cover (4) is located in the discharge chamber (2), a tungsten needle is welded and fixed at the tail end of one nickel rod, a platinum electrode is fixed at the tail end of the other nickel rod, the tungsten needle and the platinum electrode are respectively connected with the negative electrode and the positive electrode of the high-voltage power supply, the tail end of the tungsten needle is a tip, the tail end of the platinum electrode is spherical, and a high potential difference from the high-voltage power supply is formed between the tail end of the tungsten needle and the tail end of the platinum electrode.
9. The explosion-proof type discharge helium ionization detection system according to claim 1, further comprising a stainless steel tube welded on the first air inlet hole (6), the second air inlet hole (7) and the air outlet hole (8).
10. A method for preparing an explosion-proof discharge helium ionization detection system, which is characterized by comprising the explosion-proof discharge helium ionization detection system according to any one of claims 1-9, wherein the preparation method of the explosion-proof discharge helium ionization detection system comprises the following steps: s1, an oxygen-free copper sealing ring is clamped between the upper end of a discharge chamber (2) of a detector main body (1) and a CF16 flange opening of a double-electrode feed-through flange upper cover (4), a diagonal fastening screw enables the metal ring to be deformed and sealed, and a discharge end bracket (9) is fixed; s2, inserting a parallel polar plate end of a current sensor (5) into an ionization chamber (3), tightening through a through hole bolt to seal the metal edge of the current sensor (5) with an arc surface line at the lower end of the ionization chamber (3), and fixing an ionization end bracket (10) at the lower end of a detection main body (1) through a screw; s3, respectively welding stainless steel pipes on the first air inlet hole (6), the second air inlet hole (7) and the air outlet hole (8), and sleeving an explosion-proof fixing/radiating ring (13) outside the explosion-proof shell (11); S4, fixing the temperature control module, namely the heating rod and outgoing lines of the PT100, on the explosion-proof housing (11) through explosion-proof connectors (12), and fixing helium carrier gas on the explosion-proof housing (11) and the explosion-proof fixing/radiating ring (13) through the explosion-proof connectors (12), wherein the air pipe corresponding to the first air inlet hole (6) is the helium carrier gas pipe, the air pipe corresponding to the sample gas inlet hole (7) is the sample gas inlet pipe, and the exhaust pipe corresponding to the exhaust hole (8) is the straight slot hole of the tail gas exhaust pipe penetrating out of the explosion-proof housing (11).

Description

Explosion-proof discharge helium ionization detection system and preparation method thereof Technical Field The invention belongs to the technical field of gas chromatographic analysis, and particularly relates to an explosion-proof discharge helium ionization detection system and a preparation method thereof. Background The integrated development of high-end manufacturing fields such as aerospace, precision manufacturing, semiconductor production and the like, and the large-scale rapid development of the electric power industry and the petrochemical industry, and the requirement of analyzing high-purity and ultra-purity gas and trace impurity components thereof are generated. Thereby placing higher demands on the detection method and equipment, and the detection limit is required to reach ppb level. The gas chromatographic system is a classical technical means for separating and detecting complex mixed gas components, and the core components of the gas chromatographic system are a chromatographic column and a detector. The discharge helium ion detector is a universal gas detector and has a detection limit of ppb level, and can perform trace gas detection. The discharge helium ion detector has the electrode tip subjected to high voltage and high current at the moment of excitation, and continuously performs corona discharge under the working condition, and risks in the case of sudden exposure of inflammable and explosive substances in the test environment. Furthermore, the implementation of lower detection limits depends on the stability of the plasma and the high fidelity of the weak current signal trapping. The stable power supply with low output ripple and noise can enable the detector to excite more stable plasmas, and is matched with the impedance of the detector, and the power supply and signal collection cable with excellent conductive, insulating and shielding performances can improve the detection limit and the sensitivity of the detector. Current research on detector performance improvement for gas chromatography is often focused on optimizing the volume of the internal cavity, the position distance of the bias electrode and the gas path opening, and the like, while neglecting the design of air tightness improvement, the high-voltage excitation power supply of the detector configuration and the baseline noise introduced by the signal acquisition unit. Disclosure of Invention The present invention aims to solve at least one of the technical problems in the related art to some extent. Therefore, the invention aims to provide an explosion-proof discharge helium ionization detection system and a preparation method thereof, which provide references for batch preparation of explosion-proof discharge helium ion detectors and improve the detection limit and sensitivity of the whole machine. To achieve the above and other related objects, the present invention provides an explosion-proof discharge helium ionization detection system comprising: The detector main body is coaxially provided with a discharge chamber and an ionization chamber at the inner sides of the upper end and the lower end of the detector main body respectively, and the discharge chamber and the ionization chamber are communicated through needle-shaped small holes; The double-electrode feed-through flange upper cover is sealed and fixed at the upper end of the discharge chamber, and double electrodes in the double-electrode feed-through flange upper cover coaxially extend into the discharge chamber and are respectively connected with the anode and the cathode of the high-voltage power supply; the current sensor is hermetically fixed at the lower end of the ionization chamber, and extends into the ionization chamber through a parallel polar plate to obtain ion current, and a weak current acquisition module is used for collecting weak signals; and the explosion-proof shell is used for coating the detector main body and is provided with a threaded through hole and a straight slot hole for the cable and the stainless steel pipeline to pass through. In one embodiment of the present invention, Further comprises: the first air inlet hole is positioned at the side edge of the discharge chamber, and helium carrier gas is introduced from the first air inlet hole; a second air inlet hole positioned at the side of the ionization chamber, and introducing sample gas from the second air inlet hole; And an exhaust hole located at a side of the ionization chamber, from which the mixed ionized gas is exhausted. In an embodiment of the present invention, the connection sides of the discharge chamber, the ionization chamber and the needle-shaped small hole are all tapered towards the needle-shaped small hole, and the needle-shaped small hole is conical, i.e. the needle-shaped small hole is a converging vertex of two funnels, and the discharge chamber, the ionization chamber and the needle-shaped small hole are located on the same axis. In an embodiment of th