Kansas City Power & Light’s (KCP&L) Hawthorn Unit #5 is a coal fired power plant that was originally built in 1969. In 2000, the condenser had new condenser tube bundles installed with Admiralty tubes during the Hawthorn rebuild project. An evaluation of the unit in 2014 identified the potential for the conversion from open to closed cycle cooling. At the same time of the evaluation, multiple failures, causing high silica (derates), required action again in 2016. With improvements in condenser technology, and after evaluation of all the options available — including investment payback — it was decided to rebundle the condenser once again to improve the heat transfer surface area, and to anticipate the (future) requirement for the unit to operate at a higher design pressure on the circulating water side.
The current 1″ OD Admiralty Brass tubes and Muntz metal tube sheets were replaced with 7/8″ OD Titanium tubes and solid Titanium tube sheets. The waterboxes were also replaced with new carbon steel boxes, internally coated with a high solids epoxy lining, together with sacrificial anodes for cathodic protection. The new tube bundles and waterboxes were both designed for a higher design pressure. This was due to the possibility of a future cooling tower installation that would require an increased design pressure for the circulating water system. This Case Study Paper reviews the background to the requirement for new condenser tube bundles and waterboxes, compares the existing and replacement designs, reviews the installation process, and provides a summary of the project lessons learned. It is also intended to be of use to Plants that are considering changing from open to closed cooling cycle.