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NeSSI taxis for takeoff

Though acceptance and networking hurdles remain, the New Sampling/Sensor Initiative (NeSSI) is starting to emerge in real-world, standardized, modular process control applications.

02/01/2007

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Then, while improving nine gas chromatographs (GCs) at the Sarnia plant, its engineers began seeking way to increase trust in their moisture analyzer’s data and their confidence in acting on it. Lanxess’ engineers subsequently selected NeSSI-based components, including Parker Hannifin’s IntraFlow and R-Max air-actuated (DBB) stream switching system, which enabled remote validation and multi-stream analysis of one analyzer.

Canton adds that the plant’s butyl moisture sampling system now includes two membrane separators to protect the analyzer from costly flooding due to heat-trace failures. Nitrogen reference gas is dried in an on-board desiccant drier, and is used for calibration and verification. A normally closed (NC) R-Max switch direct sample flow to the analyzer, while a normally open (NO) R-Max directs the standard reference to it. In addition, bypass and analyzer flow indication is performed by Honeywell Sensotec’s 1 psig differential pressure (dP) sensors that measure pressure drops across restricted orifice plates. The sensor’s transmitter sends a 4-20 mA output to the DCS to show flow conditions (See Figure 2).

FIGURE 2: TRUE CONFIDENCE GAME     
IntraFlow Valve Switches  

Lanxess Inc. learned to trust the moisture analyzer in its butyl rubber process by securing better flow signal data with help from Parker Hannifin’s NeSSI-based IntraFlow valve switches.

 

“Resulting high-quality bypass flow signals and ‘OK to use analyzer data’ signals from the DCS eliminated costly lab sample validations and reduced time that technicians previously spent checking properly functioning systems,” says Canton. “Understanding signal limits and normal event signatures gave us benchmarks of normal operating conditions, so we’ve also established a library of abnormal condition signatures and corrective actions. Since start up the system has posted a 100% uptime record, and the analyzers’ data is regarded as absolute and conclusive.”  

Canton adds the plant’s new sampling system recently proved its worth when an unexpected moisture event was found by Lanxess’ control operators, and they learned that the analyzer detected and reported the same uncharacteristic moisture condition via the analyzer’s sample flow indicator over the DCS. “The operators reported this event would have caused a costly plant shutdown if it had happened before their new sampling tools were installed,” he says.

[Editor's note: To read the online white paper, CLICK HERE.]

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