Low-temperature catalytic conversion plus UV-DOAS, for waste incineration, cement and power plants.
Mercury in flue gas exists as elemental mercury (Hg⁰) and as oxidised compounds such as HgCl₂. Emission limits are written for total mercury (THg), so the measurement has to include both fractions.
A heated sample probe extracts flue gas and passes it through a catalytic converter held at about 200 °C. In the converter, oxidised mercury compounds are converted to elemental mercury (Hg²⁺ → Hg⁰) with a conversion efficiency above 99 %. The gas then enters a measurement cell where UV light crosses the sample, and the DOAS analyser evaluates the absorption of elemental mercury at 253.7 nm to report total mercury.
Because the converter is the only consumable part in the sample path and the optical measurement itself is contact-free, the system needs about two to three service visits per year.
The system is certified to EN 15267 with TÜV QAL1 and MCERTS. Typical requirement: EN 15267 certified range 0–10 µg/m³. Chinese method standards for mercury include HJ 917-2017 (stationary source) and HJ 910-2017 (ambient air).
| Measurement principle | Low-temperature catalytic conversion + UV-DOAS |
| Conversion temperature | 200 °C (conventional converters: 650 °C) |
| Conversion efficiency | > 99 % (Hg²⁺ → Hg⁰) |
| Detection limit | 0.5 µg/m³ (1 m path, 5 s measurement) |
| Measuring range | 0–1000 µg/m³ (Hg⁰ / THg) |
| EN 15267 certified range | 0–10 µg/m³ |
| Zero drift | < 2 % of range per year |
| Certification | TÜV QAL1 · MCERTS · CCEP |
Typical data from OPSIS product documentation; specifications depend on the application and are confirmed at quotation stage.
What is the detection limit of System 400Hg?
0.5 µg/m³ at a 1 m optical path with 5 s measurement time. The EN 15267 certified range is 0–10 µg/m³, and the maximum range is 0–1000 µg/m³ for Hg⁰ and THg.
How often does the converter need service?
Approximately two to three service visits per year. The consumables are the xenon lamp in the emitter (1–2 years) and the catalytic converter (2–3 years).
Can mercury be added to an existing OPSIS CEMS?
Yes. System 400Hg can run as a stand-alone system or share an AR600 analyser with an existing OPSIS System 400 CEMS, so mercury is measured alongside the regular CEMS parameters.
Does the system measure Hg⁰ and THg separately?
The standard configuration reports total mercury after conversion. Raw-gas elemental mercury can also be monitored directly by DOAS for flue-gas treatment control.
Send the gases, ranges, duct or path dimensions and required certification — we will respond with a technical proposal.