| 摘要 |
In the production of hot pressing quality naphthalene from naphthalene oil using continuously operating screw presses wherein the expressed oil discharged through the wall of the press is collected in at least two fractions of which that having a high naphthalene content obtained towards the end of the pressing is recycled to the initial material, the fraction formed at the beginning is split into two parts one of which is rejected while the other is distilled, top and bottom fractions being rejected and a middle, naphthalene fraction being recycled to the initial material. The amount of the first oil fraction which is rejected should be such that the amount of thionaphthene rejected is removed from the cycle to give an end product of the desired solidification point. Part of the second expressed oil fraction may also be distilled with the other, e.g. by introducing to the top of the column as a reflux. Specifications 766,371 and 812,725 are referred to. |
