Improvement Research on Furnace Flue Tube of Three Medium Dryer System Used by Fan Mills

摘要

Pulverizing system equipped by fan mills uses "three medium" (i.e. low-temperature furnace smoke, high-temperature furnace smoke, hot air) for drying coal, especially in large-scale plants burning lignite. A constantly increasing unit capacity leads to a more complicated design for pulverizing system, with a heavier weight of furnace smoke tube. This paper focuses on a research of water-cooled membrane flue tube instead of traditional inner and outer insulation tube through experiments like changing water side parameters to replace the low-temperature flue pipe from "three medium" to "two medium" (i.e. adjustable-temperature furnace smoke, hot air). This paper studies heat transfer coefficient of water-cooled furnace smoke pipe at different flow rate and flue gas temperature though a established water-cooled furnace smoke pipe test bed. It is using a certain mathematic method to obtain dimensionless relationship among Nu, Re, Pr and obtain the dimensionless rule equation of water-cooled furnace smoke tube.