Fractionation column for removing monomer from polymer suspensions - which extracts volatiles while avoiding sedimentation

摘要

A multiplate cascade column is for degassing a liquid contg. solid particles in suspension. Each plate is perforated with small holes (=5mm dia.) except for regions beneath tubes linking successive levels and for a narrow gap between each plate and the column walls. The link tubes are positioned eccentrically with respect to the column/plate axis. Device is suitable for separating residual monomers from polymer particles in a suspension, esp. for removing vinyl chloride from an aq. suspension of PVC contg. 1-60, pref. 20-40% wt. polymer. The free area at each plate level is relatively low, i.e. =8, pref. >=6% of the gross area, for operating efficiently at low gas loadings. At the same time the design avoids corners etc. on which the solid particles could settle out and build up. The liquid layers are universally agitated by the gas flow through the perforated plates, to sustain the suspension.