Chromizing for near-drum corrosion protection

During the past decade, many pulp mills have experienced severe corrosion o f generating bank tubes in the vicinity of the lower drum of two-drum-style kraft chemical recovery boilers. This phenomenon has been labeled "near-dr um" corrosion. In 1994, a trial mill developed a plan to test various produ cts and applications for controlling and ultimately eliminating this proble m. The use of chromized tubing has so far produced encouraging results and, as a result, further development of this tubing has been initiated to spec ifically address the application. This paper includes the test plan and the results, and reviews the chromizing developments mode specifically to comb at near-drum corrosion.