GB961237A - Improvements in or relating to a process of continually distilling tars - Google Patents

Abstract

In the continuous distillation of tar the tar is passed into a first vaporization zone to vaporize and separate light materials boiling below 230 DEG C. and thence into a second vaporization zone to vaporize and separate vaporizable heavy materials boiling above 230 DEG C. leaving pitch and the light and heavy vapours are fractionated in separate distillation columns from which the overhead from the heavy materials column is passed to the base of the light materials column and bottoms from the latter column is passed to the top of the heavy materials column. The tar in line 1 is heated in heat exchanger 2 with vapours from distillation column 21 and then in exchanger <FORM:0961237/C4-C5/1> 5 with hot oils from the distillation columns and passed at about 120 DEG C. into dehydration zone 7. Temperature is maintained at 140 DEG C. here by heating tar removed via line 11 by heat exchange in exchanger 14 with hot residues in line 34. Vapours in line 8 are condensed and oil returned by line 10. Tar is heated to about 250 DEG C. in heating nest 17 before passing to first vaporization zone 19 (part may be returned by line 51 to supply extra heat if required). Zone 19 is maintained at about 300 DEG C. by circulating tar through heating nest 29. Light fractions are passed as vapour by line 20 to distillation column 21. Tar next passes through heating nest 24 to the second vaporization zone 26 maintained at about 350 DEG C. by superheated steam injected through line 31. Vapours pass by line 32 to distillation column 33 and pitch is withdrawn by line 34. The two distillation columns are connected by passing liquid from the bottom of column 21 through line 37 to the top of column 22 and vapours from the latter pass by line 36 to the bottom of column 21. Heat may be supplied to column 21 by returning liquid by line 39 to vaporization zone 19. Anthracenic oil is recovered in line 40, benzol extracting oil in line 41, naphthalene in line 42, phenolic oil in line 43 and the benzolic fraction in line 3.