Processing Magazine

World’s largest PWC eases cooling tower maintenance with a fast payback

October 30, 2006

Chemical limescale treatment and manual scale removal for the process cooling of a nitric acid plant in Argentina have been eliminated thanks to a specially manufactured 16” Colloid-A-Tron in-line catalytic water conditioner from Fluid Dynamics. This is believed to be the world’s largest physical water conditioner (PWC), and is expected to provide a payback of less than two years.

Fabrica Militar Rio Tercero (FMRT) specializes in the production of a range of chemical products, including nitric acid, sulphuric acid, nitrate of ammonia and ammonium anhydride.

In the nitric acid plant, a large heat exchanger is supplied with chilled water from a cooling tower at an average flow rate of 1700m3/h (6232 gallons/minute). Within this circuit, scale was a significant problem requiring heavy dosing with chemicals and frequent shut-down for manual de-scaling. Algae in the system was also an issue, necessitating regular dosing with sodium hypochlorite to maintain control. Following detailed water testing, Fluid Dynamics was commissioned to construct a special 16-inch version of its established Colloid-A-Tron catalytic unit, believed to be the largest such unit in the world. Colloid-A-Tron units require no power, no maintenance and no chemical agents.Once the unit was installed, chemical scale treatment ceased so that the performance of the unit could be evaluated meaningfully.

After several months, it was apparent that there was no further formation of new limescale and that existing scale was also beginning to fall away. This also led to a reduction in algae, so that sodium hypochlorite dosing was reduced by 50 percent.

A year after installation, a second review showed that effective limescale control was being maintained, so it was no longer necessary to shut down the plant for manual de-scaling. These reduced maintenance costs, combined with the elimination of chemical limescale treatment and a massive reduction in algae treatment have led FMRT to predict a payback of less than two years, not including the savings achieved through increased production and reduced downtimes.