Probe fouling

Anemotherm - The Anemotherm, a hot wire anemometer, has been extensively applied to flare gas measurement and has been successfully used after modifications to reduce probe fouling. A technique used to reduce fouling is the installation of a steam coil around the tip of the probe, to prevent gases from condensing on the probe. 

What issues concerning sample system or probe fouling and process stream filtration or coalescing need... 

Probe fouling was minimized when the probe was placed properly in the reactor relative to the liquid surface and to the mechanical stirrer. The ideal spot, although not explicitly stated, would presumably be deep enough into the emulsion to see a representative bulk sample and to avoid any dead unstirred spots, but far enough from the stirrer blade to avoid impact. 

The use of second-derivative spectra eliminated the baseline shifts observed during the reaction (which could be due to changes in the amounts or size distribution of particles, or small amounts of probe fouling). 

With respect to the use of PA, the heterogeneity of the reaction systems often poses the largest technical challenge. The aspect of sampling, particularly with the elements of a representative sample size, sample presentation to analyzers and probe fouling deserve special attention in method development. Some similarities to the food or agricultural industry are... 

Probe fouling More likely More likely Less likely or not likely with noninvasive... 

Noninvasive This is seen as being the main aim of any process analysis technique. With noninvasive techniques, there is no physical contact between the analyzer and the sample. This removes any problems with sampling that may be encountered, e.g., probe fouling. 

Probe fouling and corrosion are probably the biggest issues associated with probe optics. These issues have been discussed previously. When corrosion is the problem, it is usually because of a poor material choice or a suitable material compatible with the design of the probe is not available. Some materials are so aggressive that they even slowly attack the very process pipes of which the plant is made. Process applications based on these types of materials normally require the plant operations staff to provide some level of continuous preventive maintenance to the process structure itself, thus refurbishing a probe head or probe optic presents in little additional concern. 

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