| 摘要 |
<p>In the production of titanium dioxide by the vapour phase exothermic oxidation of a titanium halide, oxide scale depositing on the internal wall surfaces of the reactor is removed during the reaction by moving over said surfaces <PICT:0822910/III/1> a scraping element internally cooled by means of ducts through which a cooling fluid is passed. In the embodiment illustrated in Fig. 1, an oxidizing gas preheated to above 350 DEG C. is introduced into cylindrical reactor 1 through conduit 2 and vaporized titanium tetrachloride is mixed therewith having been fed into the apparatus through conduit 6 and inlet 5 as a sheeted stream. In an example the top lip of this inlet is said to be externally heated. The products of reaction pass out through conduit 7 whilst a deposit 19 builds up on the reactor. The scraping device has a serrated cutting edge 15 and is supported and operated by means of a vertical hollow shaft 11 and brackets 13. The shaft 11 is provided with conventional sealing means 12. A fluid coolant such as water is supplied to the head of the scraping device through the shaft 11 and ducts 17 in the brackets 13, and removed by means of concentric ducts 18. The scraping device is rotated by a geared motor drive and vertically actuated by a hydraulic ram. It may be moved intermittently preferably before 40% of the area of the reactor is blocked or it may be moved continuously. Removed oxide scale falls through the scraping device and is withdrawn through a shoot 8 adapted to be closed from the atmosphere. Alternatively the scale may be removed with the gaseous product suspension and subsequently separated therefrom. Scraper heads consisting of segments of a circle or of arms provided with cutting edges which project from the rotatable shaft or of a helix supported by projecting arms from the rotatable shaft, are mentioned. Examples refer to the use of the invention in the oxidation of a mixture of titanium tetrachloride, preheated to 950 DEG C., with or without aluminium chloride with humid air obtained by preheating dry air to 1030 DEG C. and burning acetylene therein.</p> |
