Monitor for heat-exchanger fouling

Monitor for heat-exchanger fouling

Monitoring fouling in heat exchangers is an inexact business that typically involves watching heat transfer rate deteriorate by checking thermocouples. Now, Argonne National Laboratory has developed a heat transfer monitor that not only measures fouling, but helps find a solution. Argonne's device is an actual heat-exchanger tube, equipped with a heating block that is instrumented and electrically heated. The unit is connected to a slipstream at a plant. When fouling is detected, "we look for the conditions that initiate it, then try to modify them to prevent fouling", says research engineer C.B. Panchal. Mitigation methods that can be tested with the unit include changing the temperature, increasing fluid velocity, and putting wire inserts in the tube to create turbulence. In field tests at Shell Oil Co.'s Wood River, Illinois, refinery, the monitor showed that fouling in a crude-oil preheat-train heat exchanger occurred when crude velocity was below 1.2m/s. A second test, on a two-phase flow system, will start shortly at Chevron Products Co.'s Segundo, California refinery.