Estimating transport-shifted acid dew-point surface temperatures and conditions for the avoidance of acid mists in energy recovery operations

摘要

The availability of acid dew-point correlations (for flue gases containing the precursors of sulfuric-, nitric-, hydrochloric acids, etc.) that directly relate T _(w,dp) to the participating species partial pressures (e.g., Banchero and Verhoff, 1975; Verhoff and Banchero, 1974) without the explicit need for liquid phase thermodynamic properties has led to their popularity for preliminary design estimates of onset surface temperatures for corrosive deposits. Despite the fact that these correlations cannot be used when either or both precursor partial pressures become too small, when they are invoked within their intended domains of validity, we show here that they can be conveniently used to not only quickly estimate acid dew-point temperatures in the presence of unavoidable gas phase precursor species Soret separation effects, but also to provide preliminary estimates of the surface temperatures, T _(w,AMO), associated with the local onset of acid mists in the vicinity of cooled surfaces. Our present simple theoreticalumerical methods are illustrated for the most familiar case of sulfuric acid deposits. While we indicate that increased accuracy and generality will require a more fundamental approach in which condensate thermodynamic non-ideality is explicitly introduced, we show here that prudent use of these earlier engineering correlations can lead to immediately useful preliminary estimates of both transport-shifted T _(w,dp)- and T _(w,AMO)-values.