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TRACERCO Diagnostics™ - Flow Study

The Use of a Tracer Technique to Measure Flow Maldistribution

On a major chemical plant, a newly installed waste-heat boiler was suffering recurrent tube failure with the consequent unscheduled shutdowns. Feed-water was supplied to the boiler from a header arrangement. Tube failure generally occurred in those boiler passes nearer to the feed-water pump, it was surmised that the cause of the problem was maldistribution of feed-water leading to dry-out and overheating in those passes which were water-starved.

Flow study

Tracerco engineers were called to site to test this assumption, using the TRACERCO Diagnostics™ Flow Study technique.

A pulse of a suitable aqueous radiotracer was injected at the feed-water pump and its velocity down the several take-offs to the boiler was measured using appropriately positioned pairs of radiation detectors. From this data, the volume flowrates down each of the six take-offs were measured.

It was found that the split of flow to the boiler was, indeed, asymmetrical with the last two take-offs, IJ and KL receiving excessive quantities of water with the first four take-offs comparatively starved.

Tower scan

Using the TRACERCO Diagnostics™ Flow Study, the Tracerco engineers were able to confirm the original supposition about the cause of failure. On the basis of the study, provided by the radiotracer measurements, the plant contractor agreed to modify the feed-water distribution system, free of charge, to secure a more even distribution. Radiotracer checks carried out by Tracerco after modifications demonstrated that a much more even distribution had been achieved. Very significantly, the plant modification resulted in a dramatic reduction in the rate of tube failure.

This example is illustrative of two of the important ways in which radiotracer techniques can play a key role in;

• Predictive maintenance
• Process optimization
• A reduction in downtime

The use of the TRACERCO Diagnostics™ Flow Study technology offers rapid, accurate and cost effective method of determining flows of gas, water and organic based materials.

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