Abstract: A process of evaporating a viscous polymer solution is described. The process includes: (a) providing a viscous polymer solution including at least 30 wt. % of solvents and monomers; (b) introducing the viscous polymer solution into a heated helix (5), the heated helix having a vapor exit velocity of 200 to 300 m/s, (a film flow including a two-phase mixture of polymer melt, and solvent vapors and monomer vapors being formed within the helix); (c) forwarding the film flow from helix (5) into a heated vapor separator (6); (d) expanding the two-phase mixture of polymer melt, and solvent vapors and monomer vapors of the film flow within vapor separator (6) at an absolute pressure of 10 mbar to 800 mbar, (a bottom product including a concentrated melt of the polymer is formed within the vapor separator); and (e) withdrawing the bottom product from vapor separator (6).

Abstract: The invention relates to a method for carrying out polycondensation reactions, according to which the polycondensation of a monomeric starting material is carried out with external supply of heat in a reactor combination which has at least two stages and is composed of a pre-reactor and a high-viscosity reactor, where the low-molecular-weight elimination products produced are removed by evaporation. In the pre-reactor, the reaction product is concentrated to give a high-viscosity preliminary product. The high-viscosity preliminary product is then fed to the high-viscosity reactor, in which it reacts to completion with simultaneous introduction of thermal and mechanical energy and with a residence time of from 20 s to 60 min to give a polycondensation product.

Abstract: In concentrating solutions containing 1 to 10% by weight of salts and resins, the yield and economics and trouble-free running can be improved by using a flow tube which has a steady curvature at least in the last third and is sized in its diameter in such a way that the mean flow velocity at the tube outlet is at least 50 m/second, and at least 90% by weight of the vaporizable components are evaporated off at driving temperature gradients of 20.degree. to 200.degree. C. between the heating medium and the solution.

Abstract: In concentrating polymer solutions up to a desired specification level of residual solvents, encrustations can be prevented and the yield and the degree of purity can be increased, when the product is heated up under pressure, expanded through a restrictor element (3) with vapor formation into a first, preferably coiled flow pipe (7) and concentrated therein as far as possible, the mixture of vapors and polymer solution is whirled at an angle into a second flow pipe (9) in a sloping arrangement and fitted with self-cleaning elements (11, 12) and concentrated therein up to the desired level, and vapors and concentrate are separately discharged only downstream thereof.

Abstract: In the thermal separation of solutions and suspensions into a free-flowing solid and into a largely solid-free distillate, the useful product can be almost completely recovered in a pure state, and the amount of waste product can thus be reduced, by carrying out the concentrating in a first heatable flow pipe (6) up to an upper limit which is given by a creeping coverage of the inside wall with solid and/or by a total blockage of the flow cross-section and then continuing the concentrating in a second flow pipe (9) which is made as a rotary pipe or as a paddle shaft apparatus and whose inside wall (12) is scraped continuously, and separating the vapors and solids from one another at the end of this flow pipe (9).