Recovering solvent from paint-residue slurry - by continuous distillation, preheating it by mixing or heated exchange with already heat slurry

摘要

The process is carried out by continuous distillation whilst the slurry (from 9) is pre-heated (e.g. by mixing in pump (2) with already heated slurry in the vessel (1)). The pre-heated slurry is introduced (16) into the vessel in the upper part of the controlled volume contained therein above the heated region (3), this heated region (3) being in the upper part of the contents. The vapour moves continuously (30) to a condenser (7) and the residue flows cortinuously from the bottom (18,19) of the vessel whilst a pump (2) continuously moves slurry (14) from below the heated zone (3) and recirculates it (16) to the vessel (above the region (3)). The process avoids caking of solids which are difficult to remove, require down-time and impair heat transfer. It requires no addition, e.g. of dilute aqueous alkaline solution, prior to distillation and water rinse after distillation. It avoids extreme conditions and thus the need for special materials of construction. Capable of handling up to 40 wt.% solids and is applicable to slurries containing one or more organic solvents, resins, resinous oils, pigments and/or dyestuffs.