CONDITIONING OF FILTER BAGS WITH REACTIVE CaO AND Ca(OH)2 DUST IN FLUE GAS

摘要

Gas cleaning from reactive dusts is an issue in reactive flue gas cleaning processes. Changes in the specific dust volume due to reactions are especially challenging for filter media, leading to possible pore clogging and filter media blinding. A conditioning period of 120 h for two types of textile filter bags in a reactive atmosphere of artificial flue gas is simulated in an experimental setup at elevated temperature. The evolution of the filter cloth permeability and specific cake resistance are presented. In addition a novel method to determine apparent inhomogeneities of the filter media is applied. For all test series it is found that filtration is also possible in the long term. The final cloth permeability after conditioning is lower for CaO dust than for Ca(OH)2, and is higher than zero, and semi-continuous filter operation is possible with every investigated cloth - dust combination. It is found that even an almost new filter cloth exhibits distinctive spatial differences in permeability. The decrease of the mean permeability value is mainly attributed to a shift of this permeability profile, rather than homogeneous filter blinding.