Abstract: A process for the purification of toluenediisocyanate by fractionating a crude distillation feed containing toluenediisocyante, an organic solvent and less than 2% by weight of phosgene in a heat integrated system having an upstream distillation column, an interchanger and a downstream distillation column which are connected in series. The vapor which is recovered from the upstream distillation column is used to reboil the bottoms product of the downstream distillation column or the feed to the downstream distillation column in the interchanger. The crude distillation feed comprising less than 2% by weight of phosgene is fractionated into three product fractions P1-P3 and optionally a fourth fraction P4. P1 is a noncondensible gas stream enriched with phosgene and/or low-boilers. P2 is a solvent-enriched product. P3 is a high boiler enriched bottoms product comprising toluenediisocyanate, and P4 is a toluenediisocyanate enriched stream lean in highboilers and reaction residues.

Abstract: In the rotationally symmetrical screen for fiber suspensions with a series of straight profiled bars which extend the direction of the screen axis and form slot-shaped screen openings between them, and with several ring-shaped profiled bar supports lying in planes extending perpendicularly to the screen axis, each of the profiled bar supports having in its edge region adjacent to the inlet side of the screen a series of cutouts opening towards the inlet side of the screen for insertion of the profiled bars, with the shape of these cutouts corresponding to the configuration of the cross-sectional regions of the profiled bars held positively in these cutouts, in order to simplify insertion of the profiled bars into the cutouts of the profiled bar supports each profiled bar has for each profiled bar support a recess which decreases the width of this cross-sectional region of the profiled bar, and the recesses lie outside the profiled bar supports in the finished screen.

Abstract: A process for the purification of toluenediisocyanate by fractionating a crude distillation feed containing toluenediisocyante, an organic solvent and less than 2% by weight of phosgene in a heat integrated system having an upstream distillation column, an interchanger and a downstream distillation column which are connected in series. The vapor which is recovered from the upstream distillation column is used to reboil the bottoms product of the downstream distillation column or the feed to the downstream distillation column in the interchanger. The crude distillation feed comprising less than 2% by weight of phosgene is fractionated into three product fractions P1-P3 and optionally a fourth fraction P4. P1 is a noncondensible gas stream enriched with phosgene and/or low-boilers. P2 is a solvent -enriched product. P3 is a high boiler enriched bottoms product comprising toluenediisocyanate, and P4 is a toluenediisocyanate enriched stream lean in highboilers and reaction residues.

Abstract: In a rotationally symmetrical screen for fiber suspensions with a series of straight profiled bars which extend in the direction of the screen axis and form slot-shaped screen openings between them, and with several ring-shaped profiled bar supports lying in planes extending perpendicularly to the screen axis, each of the profiled bar supports having in its edge region adjacent to the inlet side of the screen a series of cutouts opening towards the inlet side of the screen for insertion of the profiled bars, with the shape of these cutouts corresponding to the configuration of the cross-sectional regions of the profiled bars held positively in these cutouts, in order to simplify insertion of the profiled bars into the cutouts of the profiled bar supports each profiled bar has for each profiled bar support a recess which decreases the width of this cross-sectional region of the profiled bar, and the recesses lie outside the profiled bar supports in the finished screen.

Abstract: A rotationally symmetrical screen for fiber suspensions with an inlet and outlet side, having a series of profiled bars which extend transversely to the circumferential direction of the screen, the cross-section of the profiled bars having a first end region facing away from the screen outlet side and a second end region facing away from the screen inlet side, and with metallic supporting rings lying in planes extending perpendicularly to the screen axis, each of the supporting rings having a series of cutouts open at their edge towards the screen inlet side, the shape of the cutouts corresponding to the configuration of the second cross-sectional end regions of the profiled bars lying in the cutouts, and forming an undercut in which a projection of the profiled bar cross section engages so that the profiled bars are held positively in a radial direction in relation to the screen axis and in the circumferential direction of the screen with their second cross-sectional end regions in the supporting ring cutout

Abstract: Carbon monoxide is produced in an improved process in a carbon-filled, water-cooled generator in the configuration of a truncated cone in the longitudinal section, by the gasification of said carbon with a mixed gas of oxygen and carbon dioxide, wherein the improvement comprises injecting the mixed gas into the generator through at least one downwardly-directed, coolable nozzle arranged in the generator sidewall and removing the carbon monoxide formed.

Abstract: Solutions of phosgene, an organic solvent and nitrogen or oxygen compounds which have a higher boiling point than the solvent are evaporated in a vacuum which is produced by a liquid ring pump operated on a phosgene-containing solvent as working fluid, the used working fluid being subsequently returned to the process.

Abstract: A process for pre-phosgenating organic primary amines is provided wherein a phosgene solution and an amine solution are combined in the suction side of a multiple stage rotary pump.