鴻盛科儀有限公司(鸿盛科仪有限公司)
   GREEN TREE SCIENTIFIC & INSTRUMENT CO.
NIC Product
Mercury Analyzers
Continuous Emission Monitor for flus gas
DM-6 (Total Hg) & DM-6A/MS-1A (Hg Speciation)
Mercury (Hg) is released into the environment primarily through combustion of mercury-containing material, such as coal, and solid waste from facilities like Coal-Fired Boilers and Municipal Waste Incinerators in the each country. In some cases mercury emissions can be carried for hundreds of miles before bring deposited on land and in water. Estimated, fifty percent of the mercury emitted from coal-fired power plants can travel up to 600 miles from its source. Mercury is a hazardous pollutant that causes serious adverse health and environmental effects. When mercury enters water from the air by deposition, it is converted to methyl-mercury and taken up into the food chain. Unlike other air pollutants, mercury poses a public health threat through ingestion, and less on inhalation.

Due to the above increase level of mercury emissions, the United States Environmental Protection Agency (USEPA) is pushing ahead to regulate the mercury emitted from coal-fired power plants, which is the current largest, unregulated source of mercury emissions in North America (similarly to many other countries too). With this upcoming regulation, Mercury Continuous Emission Monitors (CEM) will be deployed in each facility to continuous monitor the level of mercury emitted out of the stack.
The Mercury monitor DM-6 is a 'true' continuous monitor for mercury in stack gas, applicable for both waste incinerators and coal-fired boiler utilities. It utilizes a "solid-state reducing catalyst" housed in the DM-6P (Probe) module where all mercury reduction is done at stack. Reduced mercury (elemental) is dehumidified and transferred via Teflon tube down to the DM-6D (Detector) module to measure by continuous Cold Vapor Atomic Absorption.
DM-6
DM-6 (Dry-Catalyst Technology) offers the superior features like:
  1. Quick & Reagent-less Maintenance (done once a month within 2 hours as compared twice a week (6 hours or more each) on traditional wet-chemical method)
  2. No need for expensive and bulky heated transfer line between stack sampling and instrument
  3. Quick response time < less than 1 minutes (<20m between Probe & Detector module)
  4. No wet-chemical waste generation or disposal. Condensate generated from the emission gases in the probe module continuously pumps it back into the stack
  5. Compact Probe and Detector design
  6. High sensitivity down to 0.1ug/m3
  7. No require for bottle gas (eg. UHP Argon) operation - makes continuous monitor less maintenance and running cost.

Principle of Operation

This analyzer consists of two devices-the pre-treatment unit with probe (mounted at stack) and the mercury detector unit (set in monitor room). These two devices are portable and ready to measure by connecting each other with Teflon tube.

Mercury compounds like HgCl2 exist in the sample gas stream as well as elemental mercury. They should be all converted to elemental mercury for measurement.

In the pre-treatment unit, DM-6P, the sample gas is drawn through a filter to remove dust and then mercury compounds are reduced to elemental mercury by contacting with the solid-state reduction catalyzer. The reduced elemental mercury is subsequently dried (dehumidified condensate is continuously pumped back into the stack) and then transferred to the detector via teflon tube to be continuously measured by cold-vapor atomic absorption. LCD display shows the mercury concentration in every seconds and the detector unit has outputs for external computer and recorder for data logging and recording functions.
Model DM-6A/MS-1A is a 'true' continuous Mercury Speciator - Hgo and Hg2+, for stack gases either from coal-fired boiler utilities or waste incinerators.

Using the technique of wet-chemistry continuous flow, Hgo and Hg2+ is continuously separated, reduced and dehumidified before measuring via dual-individual channel of Cold Vapor Atomic Absorption. DM-6A/MS-1A exhibits high sensitivity (down to 0.1ug/m3) with simplified operation.

DM-6A/MS-1A
Principle of Operation

First, sample gas and a certain solution are mixed in a reaction tube (a tube that allows the gas and liquid to contact) to remove water-soluble mercury Hg2+. The gas and solution are then separated in a gas/liquid-separating tube. Interference gases such as SO2 are removed in KOH scrubber. The gas is guided to the detector (1) via a dehumidification tube where measurement for gaseous metallic mercury (Hg0) is conducted.

A solution containing Hg2+ is guided to the lower part of the reaction tube to be mixed with a reducing solution (SnCl2). There, Hg2+ in the solution is reduced to gaseous metallic mercury, which becomes a gas at the gas/liquid-separating tube. Interference gases such as SO2 are removed in the KOH scrubber. The gas is guided to the detector (2) for measurement via a dehumidification tube. Measurement data obtained here is for Hg2+. Dehumidified condensation is automatically drained regularly by peristaltic pumps.