Technical Resources

Fouling is especially prevalent in cooling water towers and systems. Small suspended solids and organisms are present in the circulating water and result in a wide range of problems and costs for the entire system. In the top 20 refineries in the United States, approximately 5 – 16 million dollars per year per refinery are spent on cooling water fouling, which is estimated as 35% of all fouling occurring in a refinery (calculations detailed in Appendix A). These costs arise from energy losses, throughput cost, maintenance, and cleaning. Of the total cost of cooling water fouling, it is estimated that 25% can be saved by conducting a cooling water study to identify where flow imbalances are occurring, and investing in changes that would correct these flow imbalances as indicated below:

1. Install flow balancing valves/orifices to reduce flow to exchangers significantly exceeding their design flow and redistribute this flow to those identified significantly below their design flow. These flow balancing devices can be simulated and accurately sized using a fluid flow model.
2. Reconfigure exchangers that are below their design flow from series to parallel flow where possible. These modifications can also be simulated in detail using a fluid flow model.
3. Change the layout of the cooling water distribution system to remove booster pumps that may be starving local exchangers and providing more pumping capacity at the beginning of the system, effectively making pipe sizes larger without replacing the existing pipe in operation through the use of cooling water flow simulation software.
4. Evaluate splitting off exchangers from one cooling water tower system to another system when flow capacity is available in another cooling water tower system which can then be analyzed in detail when fluid flow models are available for both systems.
5. Redesign exchangers when other, less costly options are not viable so that their design pressure drop matches that of other exchangers in the system. The newly designed heat exchangers can be accurately evaluated in the existing cooling water system using a fluid flow model to insure their design flow is achieved (a comprehensive system wide engineering approach versus ‘hoping’ the exchanger will work as designed).

To read the 22-page technical resource in full that discusses how to "Improve Refinery Energy Efficiency", written by Chevron and EPI Engineering, please register below to download the PDF...