Research On The Abrasion Liability Of Ash In CFB Boilers And Numerical Simulation Of Molten Incinerator

For CFB boiler, large amount of materials move rapidly in the furnace and gas with large ash density flows. That leads to the abrasion of metallic components and refractory inside the boiler. Abrasion is a factor which badly influences boiler normal operation, and is one of the most common reasons for boiler shut-down.In this dissertation. after having investigated the state of abrasion of CFB boilers' heating surface, refractory and other parts, and analyzed the concerning mechanism as well as the effecting factors, together with a composition of different criteria for discriminating the abrasion property of ashes, it is being pointed out that, for predictive estimation of the influence on abrasion of various ash ingredients, it is much simpler and more comprehensive to make use of the silicon to Aluminum ratio SiO₂/Al₂O₃ and the alkaline to acid ratio J. For this purpose, a new criterion K_J for discriminating the abrasive property of ashes is being proposed. Differing from precedents, the author don't consider influence of ash in coal on abrasion any more because of characteristics of CFB boiler, and analyze the ash abrasion property purely from the ash composition aspect instead.Ashes burned from three different kinds of fuel on CFB boilers are chosen to be analyzed on cool test-bed for the abrasion property for different bed ash with different particle density at different flow velocity from the aspect of CFB boiler operation conditions. The results show that abrasion amount of tested bituminous-type ash is a little larger than gangue ash and abrasion amount of petroleum coke is the least. The result of calculations on test ash composition using abrasion index K_J shows the same order.Swirling flow molten incinerator employed for test of fly ash after garbage firing and flow field simulation is carried out for its furnace spaces. In general, the overall calculation region is regular and it is divided using regular hexahedron grids considering the excellence of regular grids. Flow process in swirling flow molten furnace is complicated and its characteristic is strong swirl flow.