Case Studies

TRACERCO Diagnostics™ Leak Study

Leaking Waste Heat Boilers Pinpointed

In the manufacture of ammonia, the process gas from the primary reformer is adiabatically reformed in the secondary reformer. The hot process gas exiting the secondary reformer is then used to generate steam in three waste heat boilers. For some time, it was suspected that one of the exchangers was leaking and an approaching short maintenance shutdown presented an ideal opportunity to repair the leak. Since inspection and repair of the leaking boilers were due, it was beneficial to know which boiler was leaking prior to the shutdown. Tracerco was asked to use its TRACERCO Diagnostics™ Leak Study to find the leaking boiler.

The test was performed by injecting an aqueous radioisotope tracer into the boiler feed water pump suction. Sensitive radiation detectors were mounted on the process exit line of each exchanger and on the pipe exiting the steam drum. The leaking boiler was detected by a gradual increase in activity in its process exit line. This increase was caused by a build-up of radioactive salts being deposited in the leaking tubes due to the vaporisation of leaked tracer solution as it entered the process gas stream. In this particular case, the 101C South and 102 C waste heat boilers showed evidence of leaks while the 101C North waster heat boiler did not. This qualitative leak test identified which boilers needed to be inspected and repaired; it reduced maintenance effort and shutdown time, leading to substantial cost savings.

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