By Kevin Shugrue, CTI Industries
In late 2007, CTI Industries was contacted to consider installing our Full Length Tube Liners into the Main Condenser at Exelon’s Schuylkill Station in Philadelphia, PA. The Air Removal tubes in the main condenser were constructed of 304 Stainless Steel and were suffering from a form of Microbe Induced Corrosion (MIC) that was caused by chlorides in the cooling water supply from the Delaware River. The 15,000+ tubes in the rest of the condenser were 90/10 CuNi and showed no effects from the chloride attack on the stainless.
The condenser at the Exelon Schuylkill Station is an older vintage CH Wheeler, two pass divided water box configuration with 16,500 tubes. The 7/8’ x 18 BWG Admiralty tubes were retubed roughly 28 years ago with a thinner 20BWG 90/10 CuNi in the main body and an 18BWG 304 Stainless Steel into the air removal section. The upper and lower halves of the condenser feature access doors located in the center of the unit.
The Air Removal tubes are located directly in the center of each of the upper water boxes and contain 252 tubes in each of the inlet passes for a total of 504 tubes. These 304 Stainless Steel tubes were found to have a corrosive film resembling an aggressive MIC attack which became a reliability issue of having to frequently identify leaking tubes and plug them. Other than some tubes being plugged in the upper few rows from a turbine blade problem years ago, the condenser tubes overall are in great shape and should provide years of trouble-free service.