Measure Ultra-Low Emissions Accurately and Reliably with Extractive CEMS Using Nafion™-Based Sample Conditioning Systems
Perma Pure, a leading innovator in the sample gas conditioning technology, won third prize in the best paper presentation category for its paper about the measurement of ultra-low emissions with extractive CEMS using Nafion™ technology, at the Petroleum and Power Automation Meet 2015 organised by ISA-Delhi and held on April 10-11, 2015 at the Eros Hotel, New Delhi.
The current continuous emission monitoring system (CEMS) industry in developing nations including India is evolving to meet the need for more accurate, continuous, and reliable monitoring of power plant and industrial smoke stack exhaust. Gas sample conditioning systems are a critical component to insure accurate measurements of pollutants using extractive CEMS and are gaining increased attention from the industry as approaches are developed to meet higher standards for air quality. Sample conditioning is one of the most important factors for insuring correct measurements because the analyser equipment results can only be as good as the sample it measures. Moisture content must be removed from the sample prior to reaching the analyser to enable an accurate measurement and to protect the life of the analyser equipment. Traditionally, condensing technology for removal of moisture from extracted sample gas has been used, mainly due to its low initial cost. However, condensing systems face several persistent problems due to the need for dust removal, inability to handle high moisture levels, and reduced performance at high ambient temperatures, resulting in a high maintenance load, high failure rate, and inaccurate measurement due to moisture interference inside the analyzer. Perma Pure’s gas conditioning systems using Nafion™ technology for moisture removal reduces overall maintenance costs, reduces equipment failure rates, and provides for more accurate measurements of low-level pollutants compared to condensing systems.
The publication presented by Perma Pure at the 2015 Petroleum and Power Automation Meet highlighted the suitability of Nafion™-based sample conditioning systems for low-level pollutant gas measurement with extractive CEMS. Next generation power and industrial plants employ Flue Gas Desulphurization (FGD) and Selective Catalytic Reduction (SCR) to reduce flue gas SOx and NOx content, respectively, by more than 90%. In order to monitor and confirm the reduction of harmful emissions at these lower levels, measured in parts-per-million, analysers must be able to measure the SOx and NOx pollutants in concentrations less than 50 ppm. In the extractive cooler-based sample conditioning system, a significant percentage of analytes are lost due to their solubility in the small quantities of liquid water always present in such systems. This may render them unsuitable for very low-level measurement of soluble analytes such as NOx and SOx. Nafion™-based dryers remove moisture in the vapor phase, thus reducing the loss of soluble analytes as no liquid water is normally present in these systems. In this paper, real world experience with Nafion™-based sample conditioning systems is presented that demonstrates their ability to preserve the analyte levels in emissions and process monitoring gas samples and allow highly accurate results over a long service life. This experience provides power plants and refineries the confidence to deploy superior systems that both improve measurement accuracy and analyzer reliability (by preventing liquid water from entering the analyser).