A general mathematical model for the total ash mass balance of CFBC

摘要

The static and dynamic total mass balance of CFBC with coal ash as bed inventory is studied. The solids are divided into a number of size groups to consider the broad size distribution of bed inventory. The mass balance includes mass flows such as ash feed in fed coal, fly ash, bottom ash drain with classifier, drainage of circulating ash. The ash attrition and resulted ash size conversion are also considered. Calculations are carried out to show and to compare the effects of attrition, classified drainage, circulatign ash drainage, and original coal size distribution. The dynamic mass balance model considers the bottom ash drain as active manipulating variable and the coupling between the pressure drop of CFBC and the primary air flow rate and is capable of reflecting qualitatively the dynamic behavior of CFBC.