Real-time linear sampling device for mass spectrometer in range of high pressure less than 20MPa

Abstract

The invention relates to a real-time linear sampling device for a mass spectrometer in a range of high pressure less than 20MPa. The sampling device comprises an independently installed stainless steel capillary tube for sampling in a high-pressure environment and a driven pump group connected to the mass spectrometer cavity. The device is characterized in that it also includes an independent single-stage differential pump group or independent two-stage differential pump group. The device provided by the invention meet the demand of sampling in a wide-range dynamic air pressure environment through ultrahigh vacuum equipment at low cost, realizes linear response of mass spectrum signals, and also can keep an optimized air pressure work environment of vacuum protected work test equipment. All the sampling meets the requirements of real-time sampling, no time delay exists, the response to trace component collection is sensitive, the device is simple in installation, and is helpful for environmental monitoring or chemical reaction basic research.

Description

technical field [0001] The invention relates to a device for sampling from the environment of extreme high pressure (10-20MPa) and complex atmosphere in the chemical industry to the mass spectrometer working area, and can also be used to provide other ultra-high vacuum equipment to sample gas from the high-pressure area. Background technique [0002] Although the working principles of mass spectrometers are different, they all require a background pressure of 10 -8 Protected in a vacuum environment of torr or lower, the working pressure generally does not exceed 10 -5 torr, which is determined by the instrument working principle of the mass spectrometry acquisition device itself and the requirements for analysis accuracy. As for the sampling environment of mass spectrometry, except for a few in-situ analysis environments for basic scientific research that can directly meet the working environment requirements of the mass spectrometer itself, most of them meet the requiremen...

AI Technical Summary

Problems solved by technology

But this sampling method has some recognized disadvantages: 1) the working pressure of the mass spectrometer changes with the sampling environment. -6 torr, the working area of ​​the mass spectrometer at 20 atmospheres may reach 10 -4 torr, at this time, the ionization region of the electric quadrupole of the mass spectrometer will produce an ionization chemical effect due to the greatly shortened molecular mean free path, and the sampling of the chemical reaction will directly affect the product signal; 2) the capillary chromatographic effect, that is, the real-time performance is not good. Different gases will produce different aging delays and cause timing broadening of the pulse signal; 3) The capillary is particularly brittle, easy to break, and difficult to replace, and its sealed ferrule is not suitable for high-pressure environments

Generally, such a complete machine only packs a set of molecular pumps. In order to ensure low pressure after sampling, the sampled gas is generally only pre-pumped through the front stage of the pump set. If the ambient pressure is high, the back-stage pump returns to the pre-pumped gas of the mass spectrometer. Will affect the sampling accuracy

[0004] Under the requirement of extreme high pressure and the requirement of mass spectrometry to dynamically respond to the high pressure changes in the sampling environment, the above commercial solutions have more limitations: 1) the stone grinding sealing ring of the glass fiber tube is difficult to fix the capillary under high pressure; 2) such It is difficult to implement the scheme for environmental sampling above 1MPa, or it has no practical value, and it has not been applied to products in this range, let alone applied to research above 10MPa; 3) It is difficult to achieve a linear response to air pressure

[0005] In addition, for the analysis of high-pressure components, it is often used to first pass through the back pressure valve, and then sample the gas released to normal pressure. Although such a collection scheme can obtain gas components, it has disadvantages: 1) Pressure relief Delay will be caused, and real-time data cannot be obtained; 2) The gas flow after decompression only has relative component information, but the air pressure cannot be reflected in the mass spectrometry signal; 3) The decompression causes rapid volume expansion and gas mixing, and the gas is in the original high-pressure space Fine distribution changes in the gas flow or time-dependent changes in the high-pressure gas flow at a fixed point cannot be reflected in the mass spectrum

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