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Monitoring On-stream Analysers

Many of the monitoring techniques suggested for inferentials can be applied to analysers. For example the performance index (0) can be used to identify excessive random error between analyser and laboratory. The CUSUM can be used to check for a bias error which can arise particularly if the analysis method does not exactly match the laboratory technique. [Pg.212]

If in addition to calibration samples, routine samples are taken of the same product then these should ideally be taken from the same point. If the previously suggested push button or automatic detection is installed then the analyser can also be checked against accurately time-stamped laboratory samples. [Pg.212]

Analyser sample delay should be minimised by locating the analyser as close as possible to the process and installing a fast loop. This takes a small stream from a high pressure point in the process, routes it close to the analyser and returns it to the process at a point where the pressure is lower. A common approach is to connect the fast loop between the discharge and suction of a product pump. It is not advisable to install the loop around a variable pressure [Pg.212]

The choice of analyser technology may be a trade-off between accuracy and speed of response. We will see in Chapter 9 that fuel gas heating value can be approximately inferred from its specific gravity or derived accurately from a full chromatographic analysis. SG analysers can be installed to give almost no delay, while chromatographs will delay the measurement by many minutes. [Pg.213]

Analyser sample conditioning should be designed to ensure the sample is clean and in the same condition as that when processed by a laboratory instrument. These recommendations and many others are covered by specialists (Reference 1). [Pg.213]


See other pages where Monitoring On-stream Analysers is mentioned: [Pg.212]    [Pg.388]   


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