| 摘要 |
1,017,580. Solvent recovery; purification of polyolefines. REXALL DRUG & CHEMICAL CO. June 25, 1964 [June 27, 1963], No. 26383/64. Heading BIB. Solvent, e.g an alkanol or a glycol, is recovered from a solution, obtained by solventextraction of metallic catalyst residues from a polyolefine, by mixing the solution with a hot hydrocarbon oil so as to volatilize the solvent. The hydrocarbon oil is preferably an aromatic oil boiling in the range of about 400-700 ‹F. Before contacting the solution with the oil, it is advantageous to concentrate the solution in order to raise the solids-content to about 20-65% by weight. In an example, the product of the polymerization of propylene, in the presence of an aluminium alkyl and titanium trichloride, is treated with a combination of isopropanol and n-heptane. The resultant solution may be concentrated up to a solids-content of 10% by weight in evaporator 1, which is operated at a pressure of about 5 p.s.i.g. The solution is then concentrated up to a solids-content of 45-65% by weight in evaporator 4. The isopropanol and heptane vapours from evaporators I and 4 are condensed in cooler 31, and the condensate is collected in tank 30. The concentrated solution withdrawn from evaporator 4 is mixed in line 15 with a heavy aromatic oil at a temperature of 500-600 ‹F., and the mixture is pumped to flash separator 6 where the remaining isopropanol and heptane are flashed off. The vapours are condensed in cooler 32, and the condensate is collected in tank 30. Part of the hydrocarbon oil and residual feed mixture withdrawn from the bottom of separator 6 is recirculated to the separator, and the remainder is burned at a temperature of 1000-1300 ‹F. in incinerator 8. The hydrocarbon oil, to be mixed with the concentrated solution from evaporator 4, is pre-heated by indirect heat exchange in incinerator 8, and is then fed to the mixing-zone via line 21. The weight of oil which is mixed with the solution is about equal to the total weight of contained soilds. The oil to be used is preferably subjected to a prior heat-treatment at a temperature of at least 800 ‹F.
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