METHOD OF EXTRACTION OF NITROGEN TRIFLUORIDE AND THE INSTALLATION FOR ITS REALIZATION Russian patent published in 2006 - IPC C01B21/83 B01D3/36 C07C17/383 

FIELD: petrochemical industry; methods and devices for extraction of nitrogen trifluoride.

SUBSTANCE: the invention is pertaining to the method of extraction of nitrogen trifluoride and the installation for its realization. The invention is pertaining to the technology extraction of thee mixed gases components by rectification. The substance of the invention consists that they developed the method of extraction of nitrogen trifluoride by the cold rectification of the base mix, which is different by the fact, that this admixture is fed into the column of the low temperature rectification with efficiency of no less than 200 theoretical plates, and at the level of the eightieth-ninetieth theoretical plate from the top at the temperature of from minus 65°C to minus 75°C, at the pressure of 1.7-1.9 MPa and at the reflux-to-product ratio of 250-270, extraction of the admixture of tetrafluoromethane and nitrogen trifluoride is conducted from the upper part of the column above the 6-th theoretical plate, and the admixture of the low-boiling components is extracted from the upper part of the dephlegmator. For realization of this method the installation has been developed including the rectification column, the dephlegmator and the boiler different by the fact, that the column is filled in by the head with the efficiency of no less than 200 theoretical plates with the inlet for the reaction mixture arranged at the level of the 80-th - 90-th theoretical plates from the top part, and with the outlet for the tetrafluoromethane and nitrogen trifluoride arranged above the 6-th theoretical plate from the top part and the outlet for the low-boiling components from the upper part of the dephlegmator and with the outlet of nitrogen trifluoride from the boiler. The method allows to separate the reaction mixture containing of no more than 0.3 mass % of tetrafluoromethane and of no more than 2 mass % of the low-boiling impurities with production of two products: the first product - nitrogen trifluoride with the contents of the main substance of no less than 99.9 mass %, with the admixture of tetrafluoromethane - of no more than 0.05 mass %; and the second product containing nitrogen trifluoride with the contents of the main substance of no less than 98 mass % and tetrafluoromethane - of no more than 1.9 mas %.

EFFECT: the invention ensures separation of the initial reaction mixture and production of two products: the first - nitrogen trifluoride with the main substance share exceeding 99 mass % and the negligible share of tetrafluoromethane; the second - nitrogen trifluoride with the main substance share of 98 mass % and tetrafluoromethane with the main substance share about 2 mass %.

3 cl, 4 ex, 4 dwg