Chemical Control of Iron Transport, Oxide Deposition and Pressure Loss in Helical Once-through Steam Generators

摘要

Iron transport, oxide deposition and pressure loss in once-through steam generators are all strongly influenced by the choice of feedwater chemistry. However, the choice of plant feedwater chemistry is also determined by the need to ensure integrity of the pressure boundary throughout the steam raising circuit. The paper describes investigations of iron transport, oxide deposition and pressure loss in a full-scale model boiler, to determine the best method available to control increasing pressure loss in AGR helical boilers by modification of the feedwater chemistry, that does not risk unacceptable damage of the boiler tubing. The influence of both pH and changing REDOX conditions are presented. A plant trial of one of the options is also described.