| 摘要 |
A continuous process for the drying and gel formation of solvent-containing gel-forming polymers, in particular polysaccharide derivatives, by flash cooling of suspensions of the polymers, and an apparatus for the drying of solvent-containing products are described. The process comprises the steps: metering the solvent-containing polymer having a solids content of 1 to 65% by weight and at a pressure of in particular ambient pressure to 6000 hPa, at a polymer temperature of 20 to 100° C. into an evaporation zone (1), the evaporation zone (1) having a pressure of 0.1 hPa to 800 hPa, cooling the polymer, in particular to a temperature of <93° C., freeing the polymer of 2 to 5% by weight of solvent with mechanical stirring, mixing and conveying of the mixture to the lower end of the evaporation zone (1) with formation of a dense gelled product layer, discharging the polymer by means of a mechanical discharge apparatus (7), optionally with further densification of the polymer, and subsequently drying the gelled polymer in a drying apparatus to a solvent content of not more than 5% by weight. The apparatus comprises at least one evaporation container (3) having an evaporation zone (1), a stirrer and a conveyor means (8), a product inlet (12), a vapour take-off (5) with connected vacuum generator, and a discharge apparatus (7) connected to the lower end of the evaporation container (3), one or more conveyor paddles (9) having thrust blades (10) which pass across the entrance of the discharge apparatus (7) at a height of not more than 5 mm, in particular 1 to 3 mm, being provided in the lowermost plane of the conveyor means (8).
|
