F-EX-1-10 Shellside Fouling from Cooling Tower Water

J. M. Chenoweth, J. W. Suitor, and R. B. Ritter

The lack of research-quality data for shellside fouling prompted HTRI to undertake an experimental project using cooling tower water as the shellside fluid. A new HTRI Shellside Fouling Research Unit (SFRU) was especially designed and constructed for these tests. Fouling studies were conducted using a cooling tower water side stream flowing on the shell side of the two small scale shell-and-tube heat exchangers of the SFRU. These studies were conducted at the Shell Chemical Company plant in Deer Park, Texas, from October 1973 through May 1976.

This report summarizes the results of these shellside fouling tests and makes a number of general observations and conclusions useful to heat exchanger designers. The limited amount of data available has prevented the development of a generalized prediction method for shellside fouling.

For these tests fouling developed slower and an asymptotic condition was much less pronounced on the shell side than has been typically observed on the tube side even though tests ran for three to six months. The fouling resistance for bundles made with "prefilmed" carbon steel tubes or stainless steel tubes was nearly the same. This was probably the consequence of the combination of the protection provided by the "prefiliming" and the carefully controlled water treatment that prevented corrosion of the carbon steel tubes. The shellside fouling resistance was less for an exchanger with a well-proportioned baffle geometry than for one with wide baffle spacing and large baffle cut when operating at nearly the same average surface temperature and crossflow velocity. The observed shellside fouling resistances were less than the recommended design values given in the TEMA Standards.