On-line monitoring system and analysis method for volatile organic compounds

Abstract

The invention belongs to the technical field of monitoring of volatile organic compounds and particularly relates to an on-line monitoring system and analysis method for volatile organic compounds. The on-line monitoring system comprises a data acquisition and transmission control system, a flue gas sampling system, a sample gas transfer pipe, a flue gas pretreatment modulation system, a gas analysis system and a temperature and pressure flow measuring system, wherein the data acquisition and transmission control system comprises a PLC (Programmable Logic Controller), a data acquisition module of the PLC and an industrial personal computer; monitoring configuration software and an SQL Server database are mounted in the industrial personal computer; the flue gas sampling system is connected with the flue gas pretreatment modulation system through the sample gas transfer pipe; and the sample gas transfer pipe is an electric tracing type constant-power sampling pipe and is made of a polytetrafluoroethylene material. The on-line monitoring system for volatile organic compounds is stable in operation, low in fault rate, high in monitoring accuracy, relatively small in error, stable in measurement and relatively low in equipment maintenance cost.

Description

technical field [0001] The invention belongs to the technical field of monitoring volatile organic compounds, and in particular relates to an online monitoring system and analysis method for volatile organic compounds. Background technique [0002] Volatile organic compounds are often expressed as VOCs. VOCs is the abbreviation of the first letter of the three words Volatile Organic Compounds. According to the definition of the World Health Organization, volatile organic compounds refer to compounds with a boiling point between 50°C and 250°C. The saturated vapor pressure at room temperature exceeds 133.32Pa, a type of organic matter that exists in the air in the form of vapor at room temperature. According to different chemical structures, it can be further divided into eight categories: alkanes, aromatics, alkenes, halogenated hydrocarbons, esters, aldehydes, ketones and others. The main components are: hydrocarbons, halogenated hydrocarbons, oxygenated hydrocarbons and n...

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Problems solved by technology

[0005] As the environmental pollution of human life becomes more and more serious, the Ministry of Environmental Protection requires online monitoring of volatile organic compounds emitted by industrial enterprises that emit pollutants, especially spraying, petrochemical production, printing and other industries. The monitoring factors include non-methane total hydrocarbons , Benzene series (benzene, toluene, xylene, etc.), due to the short period of policy introduction, the online monitoring system requires high technical requirements. At present, there are basically no chromatographs capable of online monitoring in China, and the main products rely on imports.

The main measurement principle of its products is FID (hydrogen ion flame). Due to the large difference between domestic and foreign on-site working conditions, the domestic industrial site environment is harsh, and there are a lot of corrosive gases on site. In addition, the treatment process is backward, and the flue gas often There are low temperature, high humidity, high dust and a large amount of oily substances. There are three main problems in foreign equipment in China at present: first, they cannot adapt to the domestic industrial environment, and the operation stability of system supporting facilities is poor, and the failure rate is high. Enterprise equipment The maintenance cost is high; the second is that the measured gas in the sampling device has a large dissolution loss, and the sample gas components are easily lost during the sample gas transportation process, resulting in inaccurate measurement and large errors; third, the measurement effect is unstable

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