| 摘要 |
An apparatus for the continuous xanthation of soda cellulose in the manufacture of viscose comprises a ring of cells or cavities 3 of equal volume located in a horizontal wheel 1 fixedly mounted on a rotatable shaft 2, illustrated in Figs. 1 and 2 (not shown). The wheel 1 is enclosed closed in a fixed casing with a very small clearance between the wheel and the casing to prevent as far as possible the flow of liquid or gas from one cell to another. The wheel is rotated in a stepwise or intermittent manner so that each cell in turn is subjected to the following cycle of operations. The cell is brought to the position or station a where each cell is in turn filled with soda cellulose AC. Each cell, after having been filled with soda cellulose is then brought to the position b, where it is evacuated, then to the position c, where an inert gas which does not support combustion (such as nitrogen) is introduced into the cell. Thereafter the cell is brought to the position d where carbon bisulphide is added to the soda cellulose in the cell. The cell is then brought in turn to the position e, in which nothing is added to or removed from the cell, but the mixture of soda cellulose and carbon bisulphide is caused to remain in the cell for a predetermined period of time during which xanthation of the soda cellulose is initiated. Finally, in the cycle of operations the cell is brought to the position f where its contents are discharged into one end of a main reaction vessel 4 with the aid of nitrogen introduced under pressure into the top of the cell. The reaction mixture is advanced slowly through the vessel 4 by means of the worm conveyer 5 and is continuously discharged from the other end of the vessel 4 into one end of a second vessel 6 which is provided with a mechanical stirrer 7. The vessels 4 and 6 are provided with thermostatically controlled heating jackets 10 and 11 and with explosion pressure relief chimneys 8 and 9. Cooled soda lye is introduced into the vessel 6 through feed pipes 12 and water may be introduced into the outlet end of the vessel 6 if necessary. Xanthation is completed in the vessel 6 and the xanthate dissolved in the dilute aqueous caustic soda solution to form viscose which is drawn off continuously from the outlet end of the vessel. Each cell, after having been emptied at the position f is ready for a repetition of the cycle of operations. The reaction mixture may be caused to travel through the main reaction vessel and to be discharged therefrom into the second vessel by introducing into the main reaction vessel a volatile organic liquid such as benzene or light petroleum spirit which is miscible with carbon bisulphide and can subsequently be removed from the reaction products by fractional distillation or by decantation. The interior of the main reaction vessel and the worm conveyer therein may be coated with polytetrafluoroethylene to prevent adhesion of the xanthate. |
