Constant temperature adsorption heat analyzer for atmospheric volatile organic compound measurement

Abstract

The invention relates to a constant temperature adsorption heat analyzer for atmosphere volatile organic compound measurement. The device comprises a high temperature tank, a low temperature tank, a trapping well, and a plurality of electromagnetic valves and circulating pipelines, wherein each of the high temperature tank and the low temperature tank is divided into an upper chamber and a lower chamber by a middle partition, an openable and closable check valve is arranged between each upper chamber and the corresponding lower chamber, and silicone oil with large specific heat capacity and high heat-conducting coefficient is arranged in each lower chamber so that an air source can drive the silicone oil to circulate among the lower chambers, the trapping well and the upper chambers so as to provide constant low temperature and constant high temperature for the trapping well, and the control is precise. By virtue of the plurality of electromagnetic valves, the air source can form different passages between the upper chambers and the lower chambers of the high temperature tank / the low temperature tank through the adjusting of the check valves, and therefore, the silicone oil can be driven to once enter the trapping well and the upper chambers from the lower chambers and the residual silicone oil in the trapping well can be driven to go back to the lower chambers through the same air source; furthermore, the silicone oil in the upper chambers can reflow to the lower chambers, so that the silicone oil can be recycled to prepare a high temperature / low temperature environment.

Description

technical field [0001] The invention relates to a pretreatment device for a measurement system of atmospheric volatile organic compounds, in particular to a constant temperature adsorption thermal analysis device for the measurement of atmospheric volatile organic compounds. Background technique [0002] Volatile Organic Compounds (Volatile Organic Compounds, VOCs) are important precursors of secondary pollutants such as tropospheric ozone (O3) and secondary organic aerosols (SOA) in addition to their impact on human health and the pollution of the atmospheric environment. VOCs have become the key species in the study of atmospheric compound pollution. VOCs have a large range of environmental concentration changes (the environmental concentration of typical species such as formaldehyde can reach dozens of ppb, and the environmental concentration of high-carbon aldehydes and ketones such as valeraldehyde and hexanal It is less than 0.1ppb), high reactivity, and extreme life s...

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Problems solved by technology

At home and abroad, the thermal desorption instrument combined with gas chromatography to measure VOCs mostly uses liquid nitrogen or dry ice as the refrigerant. The use of a large number of refrigerants not only increases the cost of the experiment, but also is complicated to operate, which is not suitable for field observation and on-site analysis.

[0004] Based on semiconductor refrigeration, some small cryogenic traps have been developed abroad to achieve the enrichment and concentration of VOCs. These traps generally use refrigeration chips to directly transfer low temperature to the adsorbent, and use electric heating wires to achieve high temperature thermal analysis. There are the following problems : First, the refrigerating sheet is directly attached to the trap to provide low-temperature capture. When the airflow passes through, there is a problem of unstable temperature control, and the capture efficiency is also greatly affected; second, the electric heating wire is used as a heat source for high-temperature thermal analysis. There are problems such as uneven heating and unstable analysis efficiency

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