ROLE OF VARIOUS SYSTEM PARAMETERS IN FURNACE DYNAMIC RESPONSES FOLLOWING A MASTER FUEL TRIP

摘要

The draft system of a fossil boiler may experience catastrophic negative pressure excursions in the event of a master fuel trip (MFT). Potential for such pressure excursions increases significantly if the draft system is retrofitted with flue gas desulfurization (FGD) equipment. The magnitude of negative pressure following a sudden load reduction or a MFT depends on a number of design and operating features of a plant such as: type of fuel (coal, oil or gas), fuel valve closing time, ID fan damper stroke time, ID fan damper maximum opening position, and the kicker circuit parameters. Extensive analytical studies have been made using PC-TRAX, a state-of-the-art dynamic simulation computer code, for more than half a dozen fossil plants using coal, oil or natural gas as fuel. The size of the units investigated ranged from 150 MW to 1300 MW. This paper presents the main results of this study particularly with regard to the influence of those plant design parameters which significantly affect the severity of the consequences of a MFT. The conclusions of this study should provide valuable guidance to a system engineer involved in making necessary modifications to reduce the consequences of a MFT below acceptable limits.