On-line analyzer and analysis method for wet enrichment of mercury in flue gas

Abstract

The invention belongs to the technical field of environmental monitoring and particularly relates to an on-line analyzer and an analysis method if mercury in flue gas based on wet enrichment. The analyzer comprises an enrichment system, a detection system and a control system. The analysis method comprises the following steps of enrichment reagent introduction, blank detection, sample gas enrichment, sample detection and solution discharge or storage. The analyzer has the advantages that the analyzer can realize on-line analysis of mercury (Hg<2+>, Hg<0> and total mercury) in different valent states and even analysis of different heavy metal elements by combining with a high efficiency enrichment device and an on-line X-ray fluorescent technique and through flexible selection of a chemical reagent, and detect and store samples for a laboratory off line.

Description

Technical field [0001] The invention belongs to the technical field of environmental monitoring, and specifically relates to an online analyzer and an analysis method for wet enrichment of flue gas mercury. Background technique [0002] Mercury and its compounds can enter the environment through a variety of channels, and its emissions are mainly divided into natural sources (volcanic eruptions, etc.) and man-made sources. Man-made sources are the most important source of mercury pollution, and fuel combustion is the most important aspect in man-made activities. . Studies have shown that global coal-burning mercury emissions account for about 65% of total emissions. Based on the average mercury content of coal in China at 0.188mg / Kg, the atmospheric mercury emission factor in my country’s coal-burning industry can be as high as 70%. Among them, mercury emissions from coal-fired power plants account for more than 30% of the total atmospheric mercury emissions, ranking first in the...

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Problems solved by technology

[0003] At present, the main enrichment of flue gas mercury online analyzers is through the method of gold amalgam. This method is expensive and requires high-purity carrier gas purge after enrichment, which is convenient for the subsequent use of cold atom fluorescence or cold atom. Absorption techniques are used for detection, and both cold atomic fluorescence and cold atomic absorption techniques are directly aimed at elemental mercury (Hg 0 ) detection, in order to complete the determination of mercury in different valence states, it is often necessary to convert the mercury valence state (Hg 2+ →Hg 0 ), the generally adopted methods are thermal catalytic conversion method and high temperature conversion method, wherein, the thermal catalytic conversion method converts ionic mercury into elemental mercury through catalytic reaction under the condition of 200-400 ° C, due to the adoption of catalytic reaction, The conversion temperature is lower than the high temperature conversion temperature, the catalytic treatment is relatively simple, and no chemical reagents are required, but in order to prevent catalyst poisoning, a spare conversion system needs to be configured, which brings about an increase in the cost of the instrument, and there is also a problem with the life of the catalyst; the high temperature conversion method Ionic mercury will be reduced to elemental mercury at high temperature (>800°C). This method does not require the use of chemical reagents and catalysts. The conversion method is reliable at high temperatures, but it has high requirements for instruments and pipelines. At the same time High temperature poses safety hazards and brings about an increase in overall instrument energy consumption

In addition, the above-mentioned online analysis methods are all destructive tests and cannot save samples for subsequent laboratory data verification

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