MASS TRANSPORT IN SAMPLE TRANSPORT LINES ADSORPTION DESORPTION EFFECTS AND THEIR INFLUENCE ON PROCESS ANALYTICAL MEASUREMENTS

摘要

The majority of low level concentration measurements, whether for process control, productrnquality monitoring, or emissions monitoring, are based on extractive analysis of a gas or liquidrnsample. Often the chemical species to be measured are reactive, and the physical distancernbetween the sample point and the analyzer shelter is significant. In such cases, the ability of thernsample system to reliably transport the species of interest in a timely manner is critical to suchrnmeasurements.rnImproper design of the system to meet such requirements results in unnecessary lag time andrnslow responding systems or makes accurate process gas analysis impossible. To properly employrnextractive analytical systems, factors such as response lag and sample loss due to adsorption andrnchemical reactions on the surfaces of the flow path must be considered and addressed. Therntheoretical and practical analysis of such factors and design guidelines will be presented.