Volatile organic compound double-cold trap sample introduction unit, system and method

Abstract

The invention relates to a volatile organic compound double-cold trap sample introduction unit, system and method. According to the sample introduction unit, a two-way valve V1 is arranged between a sample inlet and a first four-way valve, and a two-way valve V2 is arranged between the sample inlet and a second four-way valve; the first four-way valve communicates with the two-way valve V1, a high-carbon enriched cold trap and a first detector, and the second four-way valve communicates with the two-way valve V2, a low-carbon enriched cold trap and a second detector; a two-way valve V3 is arranged between the high-carbon enriched cold trap and the first four-way valve, and a two-way valve V4 is arranged between the low-carbon enriched cold trap and the second four-way valve; a two-way valve V5 is arranged between the first four-way valve and an exhaust hole, and a two-way valve V6 is arranged between the second four-way valve and the exhaust hole; and the first four-way valve, a firstcarrier gas inlet and the first detector communicate through a three-way valve V7, and the second four-way valve, a second carrier gas inlet and the second detector communicate through a three-way valve V8. According to the sample introduction unit, system and method, the enrichment and detection of pollutants with the relatively low concentration can be realized; and the sample introduction system can achieve full-time-period and no-time blind spot detection.

Description

technical field [0001] The invention relates to the field of environmental science, in particular to a volatile organic compound double-cold-trap sampling unit and enrichment sampling method, as well as a sampling system and method containing a plurality of volatile organic compound double-cold-trap sampling units. Background technique [0002] Volatile organic compounds (VOCs) are ubiquitous in the atmosphere and have the most serious impact on the environment. VOCs mainly come from motor vehicle emissions (43.7%), technological processes (26.0%), fixed combustion sources (19.3%), solvent paint use (6.3%), and oil storage and transportation processes (4.7%), among which motor vehicles Exhaust emissions are the most serious. It mainly includes alkanes, aromatics, olefins, halocarbons, esters, aldehydes, ketones and other organic compounds. The composition of VOCs is complex, and most of them are photochemically reactive. Under sunlight, they interact with NO in the atmosph...

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Problems solved by technology

[0004] The main problems existing in the detection methods of volatile organic pollutants in the atmosphere in the prior art are: the continuous and uninterrupted sampling of pollutant samples cannot be realized, there are sampling blind spots, and the detection results cannot reflect the overall concentration of pollutant samples value, the measurement results are inaccurate; the high-carbon components and low-carbon components in the pollutant samples cannot be effectively separated, and the enrichment efficiency is low

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