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TRACERCO Diagnostics™ - Leak Study

On-Line Diagnosis Shortens Unit Downtime

While monitoring the contamination levels in treated waste gas lines at a nitric acid plant, it was discovered that impurities (which should have been removed by the catalysts) were running high. This could either be due to a leaking feed/effluent exchanger, or to channelling in the catalyst bed. Tracerco was called in to pinpoint the problem area. A feed/effluent exchanger relies on the treated gas to heat the untreated waste gas. Tracerco used its TRACERCO Diagnostics™ Leak Study technique to investigate this problem. A small amount of gaseous tracer was injected into the process line upstream of the exchanger.

Illustration of a leak study

Radiation detectors were placed strategically on the inlet and outlet pipes of the waste gas and treated gas lines of the exchanger. In this case, they indicated that there was no leak across the exchanger and therefore, the catalyst reactor was the likely source of the problem. Further studies showed that the residence time across the reactor was considerably shorter than found on previous occasions, suggesting severe channelling in the catalyst bed. Plant management decided to change out the catalyst. Upon opening the reactor, workers discovered that the bed had collapsed; this explained the poor treatment of the waste gas. Tracerco’s elimination of the exchanger as the source of the problem, reduced the unit’s downtime by an estimated two days, and resulted in considerable savings. The diagnosis also insured that fresh catalyst was available for change out.

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