Abstract: The invention concerns a device for the cooling of hot gaseous solids suspensions, particularly for the cooling of hot gaseous TiO.sub.2 suspensions resulting from the production of titanium dioxide by vapor phase oxidation of titanium tetrachloride. The device consists of a number of coaxially connected constructional units, each of which consists of three jacketed tubes, i.e., tubes 1, 2 and 3, which are coaxially connected in such a way that tube 1 conically tapers toward tube 2 and that tube 3 is larger in diameter than tube 2. Heat transfer is twice as high in the device of the invention as in a comparable conventional cooling tube of uniform inner diameter; moreover, the demand of scrub solids needed to prevent the formation of deposits on its walls is reduced to one third of the quantity needed in a conventional cooling tube.

Abstract: The invention concerns a device for the cooling of hot gaseous solids suspensions, particularly for the cooling of hot gaseous TiO.sub.2 suspensions resulting from the production of titanium dioxide by vapor phase oxidation of titanium tetrachloride. The device consists of a number of coaxially connected constructional units, each of which consists of three jacketed tubes, i.e., tubes 1, 2 and 3, which are coaxially connected in such a way that tube 1 conically tapers toward tube 2 and that tube 3 is larger in diameter than tube 2. Heat transfer is twice as high in the device of the invention as in a comparable conventional cooling tube of uniform inner diameter; moreover, the demand of scrub solids needed to prevent the formation of deposits on its walls is reduced to one third of the quantity needed in a conventional cooling tube.