Emissions Estiation Expressions for Vessel Depressurization in Batch Chemical

摘要

Emissions estimation expressions are presented for vessel depressurization in batch chemical operation where inert gas pressurizes a VOC-containing material. The expressions are compared to the procedure in EPA's Gideline Series. An obvious first improvement is the expressions presented here apply to a wider range of conditions - both initial VOC saturation and constant VOC saturation of depressurized gas and both uncontrolled and condenser-controlled emissions. A second improvement is EPA's procedure may over-estimate emissions by employing an average VOC composition during depressurization based on an assumed linear profile between initial and final compositions. The overestimate increases with increasing initial system pressure and VOC volatility, which itself increases with temperature. A third improvement is the capability to estimate, through the use of uncontrolled and controlled emissions estimation expressions, the control device efficiency and its sensitivity to operational flexibilties, like changes in temperature, pressure and product formulation. Industrial operations benefiting from these emissions estimation expressions include depressurization following closed-vessel filtration of VOC-containing material and depressurization of a VOC-containing reaction vessel blanketed by inert gas.