Study of scale-removal methods in a double-pipe heat exchanger

The objective of the present study was to examine the effectiveness of four cleaning methods for the removal of tube-side fouling in a double-pipe hea t exchanger. The four cleaning methods are (1) hydrolazing with 10,000-psi head pressure. (2) hydrolazing with 20,000-psi head pressure, (3) chemical cleaning, and (4) brush punching. Fouled tubes were prepared using water fr om a cooling tower. Each test started with a brand new tube. When the overa ll heat transfer coefficient dropped by 40% from the initial peak value, sc ales in the fouled tubes were removed using one of the above four methods. Both the overall heat transfer coefficient and inside diameter were measure d before and after fouling, by which the effectiveness of a particular clea ning method was evaluated. The chemical cleaning method was found to be mos t effective, whereas the brush punching was least effective. When a fouled tube was kept dry, brush punching completely removed scales, indicating tha t surface wetness plays an important role in scale removal.