Laser Gas Detection module LGD F200 helps to reduce costs

Pollutant gases such as SO₂, NO, CO, HF & HCl and dust are products of combustion that are regulated by national environmental protection agencies.

Continuous Emission Monitoring Systems (CEMS) are used to permanently measure pollutants. All gases have to be corrected and reported at standard conditions defined as 0°C, atmospheric pressure 1013 mbar, dry gas. In order to have the concentration values at standard conditions, pressure, temperature and moisture measurements are required. The presence of humidity in a gas stream takes up space that would otherwise be occupied by pollutant. Therefore, the pollutant concentration expressed on a dry gas basis is higher compared to the value expressed on a wet gas basis.

All emission measurements must be reported on dry gas basis. Axetris Laser Gas Detection modules are able to measure H₂O as well as H₂O combined with NH₃ or HCl simultaneously, thus helping to reduce equipment costs and increasing long-term measurement reliability.

When the H₂O value is calculated instead of measured, the following types of oxygen analysers are necessary for the measurement:

• O₂ Wet: Measure with in-situ Zirconium Oxide analysers
• O₂ Dry: Measure with extractive paramagnetic analysers or electrochemical cells

Since H₂O is not a pollutant, this method is not subject to EN14181 QAL1 requirements.

Emissions of stack gases are usually expressed on a dry gas basis so that variation in the moisture of stack gas does not affect the assessment of the emissions.

To convert concentration values from wet gas to dry gas the following formula is used:

Dry gas concentration = Wet gas concentration × 100 Divide 100-H₂O%

Compared to the computational method based on O₂ wet and dry, the direct moisture measurement involves less complexity on equipment level leading to increased reliability over time.

Axetris AG is a designer and OEM manufacturer of Laser Gas Detection (LGD) solutions based on Tunable Diode Laser Spectroscopy (TDLS). The TDLS technology provides a valid, cost effective solution to many challenges in environmental gas monitoring and process control applications involving the measurement of gases such as NH₃, HCl, H₂O, CH₄, CO₂.

The TDLS technology offers many advantages like:

• precise optical, contactless measurements
• excellent target gas selectivity
• sub ppm-level detectivity
• low cost of ownership
• high stability and reliability in the field

The modules are designed for integration by Original Manufacturers (OEMs), operating in the field of gas detection and monitoring in diverse industries. The LGD F200 series is based on a near-infrared absorption measurement of the target gas. The systems are self-contained, ready-to-use OEM modules, using a flow-through cell set-up for extractive measurements. The LGD F200 hot version comes with a cell heated up to 220°C for hot gas measurements in process control and environmental compliance related applications. The LGD F200 module comes with proprietary digital signal processing providing reliable measurements data through an analog and digital data interface.

Key features of the Axetris LGD F200

• Made for easy integration by OEMs
• Fast response
• Selfcontained
• Continuous sensor status monitoring
• Low maintenance
• 10-30V DC power supply
• Digital and analog data interfaces
• Hot-gas measurement up to 220°C

Axetris supports their OEM customers with in-depth technology and application expertise from feasibilities until product launch. The Axetris team collaborates with their customers in finding the right product design which best suits their needs in terms of performance and costs. As an OEM partner, Axetris assists with setting-up the infrastructure and with technical training.

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