Volatile organic compound on-line monitoring method and system

Abstract

The invention discloses a volatile organic compound on-line monitoring method and system, and the method comprises the steps: filling a liquid phase region in a sampling container with a collected experimental liquid phase sample through a liquid phase sample injection port arranged at the top of the sampling container; stirring and disturbing the experimental liquid-phase sample until gas-liquid two-phase dynamic balance is achieved; the gas phase concentration value of the sampling container is obtained through a concentration sensor, and the liquid phase concentration value of an experimental liquid phase sample in the sampling container is obtained through experimental analysis; taking the ratio of the gas phase concentration value to the liquid phase concentration value as a gas-liquid distribution constant of a preset calculation model; when the underground water is monitored in real time, the gas phase concentration value collected by the concentration sensor in real time is used as input, and the real-time total volatile organic compound concentration of the underground water is calculated according to a preset calculation model. The total concentration of the volatile organic compounds in the underground water sample can be calculated directly according to the gas phase concentration value collected by the concentration sensor in the sampling container, so that the accuracy and the real-time performance of a monitoring result can be improved.

Description

technical field [0001] The invention relates to the field of environmental protection, in particular to a method and system for online monitoring of volatile organic compounds. Background technique [0002] In the petrochemical industry, in the process of oil extraction, transportation, processing, storage, etc., accidents such as dripping and leakage occur from time to time, and the above accidents are likely to cause pollution to the soil and groundwater of petrochemical sites. Therefore, the monitoring of soil and groundwater pollution in petrochemical sites plays an important role in the prevention and control of environmental pollution. [0003] Groundwater organic pollutants in petrochemical sites are mainly volatile organic compounds. Volatile organic compounds generally refer to a class of organic compounds with a boiling point less than 260°C and a saturated vapor pressure greater than 133.322kPa at room temperature, and are an important class of air pollutants. V...

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Problems solved by technology

[0004] At present, the monitoring of pollutants in petrochemical sites mainly relies on manual sampling and laboratory analysis; the inventors have found through research that since most volatile organic compounds in groundwater are non-polar or weakly polar substances, when the temperature changes , pressure changes or environmental changes such as disturbances, it is easy to cause the escape of volatile organic compounds in the water; therefore, the pollutant monitoring methods in the prior art will cause groundwater to Volatile organic compounds are lost, and the analysis process takes a long time, so the monitoring results lack accuracy and real-time performance, which is not conducive to the real-time monitoring and pollution warning of VOCs on the site

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