Operational and Chemistry Modelling and Monitoring of Cooling Water Heat Exchangers for the Avoidance of Waterside Fouling
August 19, 2019
Author: E. S. Beardwood. Heat Exchanger Fouling and Cleaning, Dublin, Ireland, June 7-12, 2015. http://heatexchanger-fouling.com/, now operated by HTRI (Heat Transfer Research Incorporated)
ABSTRACT: This paper will outline problem solving methods utilized to identify reliability and performance short comings associated with an overhead cooling water heat exchanger in the chemical processing environment. Modeling of both the heat exchanger operational conditions compared to design and the cooling water chemistry resulted in small changes in operational conditions, chemistry enhancement and metallurgical upgrading of the heat exchanger tubing. The implementation of the findings resulted in increased life of heat exchanger tubing, removal of the need for annual tube cleaning with a hydro-cutter and improved fouling run rates less than the design fouling allowance of the heat exchanger. The site heat exchanger actual operational conditions were modeled hydrodynamically, then a simulation modeling program was applied to duplicate the operating conditions of the test heat exchanger in the laboratory and side stream in the actual cooling system. The chemistry enhancement was selected based upon the foulant type and hydrodynamic stress found from the model and laboratory trial runs at various operational cooling water stress levels. The operational and chemistry changes were then validated in the actual cooling water system with heat transfer monitoring equipment that duplicate surface temperature and shear stress of the site heat exchanger of concern. This problem solving approach resulted in a 66 % reduction in fouling rates and the monthly mechanical cleaning of the inorganic scales has not been required for the past 10 years.