Continuous Mercury Emission Monitoring System

What is the Continuous Mercury Emission Monitoring System?

A continuous mercury emission monitoring system measures mercury in industrial stack gas in real time. It is chosen for compliance with emission limits at waste incinerators, power plants and cement or metal facilities.

Overview

This system extracts a representative gas sample through a heated, inert sample line to prevent mercury loss and condensation. Mercury may be measured directly by Zeeman atomic absorption or ultraviolet absorption, or converted and concentrated on a gold amalgamator for periodic measurement. Some designs use sorbent traps that are analyzed later. A converter reduces oxidized mercury to elemental form so that total mercury is measured, and moisture and particulate removal protect the analyzer. Calibration uses an integrated gas-phase mercury generator and certified reference gases, with daily or periodic system checks. Data are reported as mass concentration and can be converted to emission mass per unit time. Systems are designed for continuous duty, with heated lines, automatic zero and span checks, and reporting formats that match emission regulations.

How does it work?

Mercury is unique among metals because it is volatile at room temperature and forms a stable amalgam with gold. Most analyzers exploit one or both properties. In cold vapor atomic absorption, mercury in solution is reduced to elemental form with tin chloride or sodium borohydride and swept into an absorption cell where it absorbs the 253.7 nanometre line of a mercury lamp. Cold vapor atomic fluorescence uses the same generation step but detects emitted light at right angles for higher sensitivity. Direct analyzers heat the solid or liquid sample to release mercury, which is collected on a gold amalgamator, then desorbed into a detector. Ambient air and emission monitors use gold amalgamation or optical techniques such as Zeeman atomic absorption or ultraviolet absorption for continuous measurement. Calibration uses certified mercury standards and gas-phase generators, and all systems require careful control of contamination because mercury is ubiquitous in laboratories.

What are the key features?

• Heated inert sample line to prevent mercury loss
• Total mercury conversion of oxidized species
• Zeeman, ultraviolet or gold amalgamation measurement
• Integrated gas-phase mercury calibrator
• Automatic zero and span checks
• Reporting formats matched to emission regulations

What are the technical specifications?

A typical continuous mercury emission monitoring system configuration offers measurement range of 0–100 µg/m3 or higher, detection limit of 0.1–1 µg/m3, response time of 60–180 s, sample line temperature of 120–180 °C, detection principle of Zeeman AAS, UV or amalgamation and calibration of gas-phase mercury generator. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Continuous Mercury Emission Monitoring System is used in waste incineration stack emission compliance, coal-fired power plant mercury monitoring, cement kiln and metal smelter emissions and industrial process gas mercury control. Across the wider Mercury Analyzers class, laboratories also deploy it for mercury in fish, rice, seafood and food products, drinking water, wastewater and seawater monitoring and soil, sediment and contaminated site assessment.

Which standards and certifications apply?

Relevant standards and methods include US EPA Method 7473 Mercury in solids and solutions by thermal decomposition, US EPA Method 7470A Mercury in liquid waste by cold vapor AAS, US EPA Method 1631 Mercury in water by oxidation, purge and trap, and CVAFS, ISO 12846 Water quality — Determination of mercury by AAS after enrichment, ISO 20552 Workplace air — Determination of mercury vapour by gold amalgamation, EN 15852 Stationary source emissions — Determination of total gaseous mercury and IEC 61010-1. Certification candidates for this model are CE, EN 15267 QAL1 suitability and ISO 9001 manufacturing; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Mercury is toxic by inhalation and accumulates, so laboratories must control vapor exposure, use ventilated enclosures and monitor ambient air. Contamination is a constant risk because mercury appears in reagents, dust and previous samples, so ultrapure reagents, dedicated glassware and rigorous blanks are essential. Gold amalgamators require periodic cleaning or replacement when recovery falls. Calibration standards and gas generators must be traceable, and reducing agents must be fresh. Luminaires and detectors for the 253.7 nanometre line need stable temperature. For emission and ambient monitors, sample lines must be heated and inert to prevent mercury loss. Maintain service records and follow local occupational exposure limits and waste disposal rules.

How do I select the right Continuous Mercury Emission Monitoring System?

Select a continuous monitoring system when an emission limit must be demonstrated continuously and data must be reported to a regulator. Specify the expected concentration range, gas composition, moisture and particulate loading, and the required reporting standard. Confirm heated line length, calibration method and that the system meets any national approval or suitability scheme.

How does it compare with other Mercury Analyzers variants?

Select a mercury analyzer by sample type and required detection limit. Direct thermal decomposition analyzers handle solid and liquid samples in minutes with minimal preparation and reach low nanogram levels, which suits food, soil and waste testing. Cold vapor atomic absorption is a robust, economical choice for water and digested samples at microgram per litre levels. Cold vapor atomic fluorescence reaches much lower limits and suits ultratrace water and seawater work. Portable ambient air analyzers with gold film or Zeeman detection serve workplace and indoor air surveys. Continuous emission monitors and total mercury analyzers with gold amalgamation are installed on industrial stacks and process streams. Confirm the measurement range, sample throughput, calibration approach and whether a specific regulatory method is mandated.