Cold-Dry Extractive CEMS with Sample Conditioning

What is the Cold-Dry Extractive CEMS with Sample Conditioning?

An extractive system that cools the sample to about 4 °C to remove water before measuring SO2, NOx, CO, CO2 and O2 on a dry basis. It is the right choice for combustion sources where gases are not water soluble and lowest instrument cost matters.

Overview

This system uses a heated probe and line to carry sample to a sample conditioning unit where a thermoelectric or compressor cooler drops the dew point to 3 to 5 °C and a peristaltic pump removes condensate. The dry gas is then supplied to individual analyzers: NDIR or UV for SO2, chemiluminescence for NOx, NDIR for CO and CO2 and a paramagnetic or zirconia sensor for O2. Measurement is on a dry basis, matching many regulatory limits without correction. Because some SO2 and NO2 can dissolve into condensate, converters and fast chillers are designed to limit losses. The design is modular, serviceable and uses widely available analyzers, making it the most common CEMS type for boilers, gas turbines and kilns.

How does it work?

Emission monitors determine pollutants in hot, wet and dusty flue gas. Extractive systems withdraw a sample through a heated probe and line at 180 °C, remove particles with a filter, and either keep the gas hot for analysis or dry it in a chiller before measurement. Analyzers use non-dispersive infrared for CO, CO2 and SO2, chemiluminescence or UV for NOx, paramagnetic or zirconia cells for O2, and FTIR for multi-component measurement. In-situ systems measure across the stack using tunable diode laser absorption or UV. Particulate monitors use light scattering, transmissometry for opacity, or triboelectric signals, and flow is measured by differential pressure pitot tubes or ultrasonic transit time. A data acquisition system normalizes values to reference oxygen, dry basis and standard conditions, applies calibration and reports averages.

What are the key features?

• Thermoelectric chiller dries sample to a 4 °C dew point for stable analyzer operation.
• Modular analyzers allow each component to be serviced or replaced independently.
• Dry-basis measurement matches the reporting basis of most emission regulations.
• Peristaltic condensate pumps and moisture sensors protect analyzers from liquid carryover.
• Automatic calibration valves route zero and span gas to the probe for full-path checks.
• Optional NOx converter for NO2 reduction supports total NOx reporting.

What are the technical specifications?

A typical cold-dry extractive cems with sample conditioning configuration offers measured components of SO2, NOx, CO, CO2, O2, SO2 range of 0–300 / 0–3000 mg/m³, NOx range of 0–250 / 0–1000 mg/m³, CO range of 0–100 / 0–3000 mg/m³, O2 range of 0–25 vol% and sample dew point after cooler of 3–5 °C. 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 Cold-Dry Extractive CEMS with Sample Conditioning is used in coal and oil-fired boilers, gas turbines and engines, cement and lime kilns and steel and glass furnaces. Across the wider Emission Monitoring class, laboratories also deploy it for coal and gas power plant stacks, cement and lime kiln emissions and waste incineration monitoring.

Which standards and certifications apply?

Relevant standards and methods include EN 14181, EN 15267-3, EN 15259, ISO 12039, US EPA 40 CFR Part 60, US EPA 40 CFR Part 75, HJ 75 and HJ 76. Certification candidates for this model are CE, China CEMS certification and EN 15267 QAL1; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Choose sampling locations that meet EN 15259 or HJ/T 397 requirements for straight duct length and port access, because flow profile affects representativeness. Keep heated lines above the acid dew point to prevent condensation and corrosion, and replace probe filters and pump heads regularly. Perform daily automatic zero and span checks, quarterly or annual linearity checks, and an annual surveillance test against a standard reference method under EN 14181 QAL3 and AST. Protect cabinets from dust and temperature extremes, and provide calibration gas cylinders with certified uncertainties. Keep records of maintenance, calibration and data substitution, since regulators audit these, and train operators in safe work on platforms.

How do I select the right Cold-Dry Extractive CEMS with Sample Conditioning?

Select cold-dry when measuring common combustion gases on a dry basis and wanting simple, widely serviceable hardware. It is unsuitable for highly soluble gases like HCl or NH3. In an RFQ, specify gas list, ranges, sample conditions, calibration gas supply, enclosure type and required certificates.

How does it compare with other Emission Monitoring variants?

Start with the regulated pollutants, emission limits and the standard your permit cites, such as EN 14181 or HJ 75. Decide between extractive and in-situ systems according to stack temperature, moisture, acid gas content and the number of species: extractive suits multi-component and low-level measurements, while in-situ suits single gases and fast response. Check that measurement ranges are suitable for the limits, with limits in the lower third of the range where possible. Consider reporting requirements for averaging, data validation and certified instrument status under schemes such as EN 15267 or China CEMS certification. Include sample conditioning maintenance, calibration gas logistics, shelter size and the ability to cope with wet scrubber stacks.