US 8,524,070 B2 · Method for processing hydrocarbon pyrolysis effluent

Abstract

A method and apparatus are disclosed for treating the effluent from a hydrocarbon pyrolysis unit employing a small primary fractionator, i.e., a rectifier. The method comprises cooling the gaseous effluent, e.g., by direct quench and/or at least one primary heat exchanger, and then cooling the gaseous effluent to a temperature at which tar, formed by reactions among constituents of the effluent, condenses, e.g., in a secondary exchanger. The resulting mixed gaseous and liquid effluent is passed through a rectifier, to cleanly separate quench oil from the gaseous effluent comprising a pyrolysis gasoline fraction, whose boiling point can be lowered as a result of the rectifier treatment. The effluent is then cooled to condense a liquid effluent comprising pyrolysis gasoline and water condensed from steam, which fractions are separated in a distillate drum. The cooled gaseous effluent is directed to a recovery train to recover light olefins. At least a portion of the pyrolysis gasoline-containing fraction can be recycled to the rectifier to enhance separation of the quench oil from the pyrolysis gasoline fraction.

Claims23

Dependent claims

A method for treating gaseous effluent from a hydrocarbon pyrolysis unit, the method comprising:

(a) cooling said gaseous effluent at least to a temperature at which tar, formed by reaction among constituents of the gaseous effluent, condenses;
(b) passing a mixed gaseous and liquid effluent from step (a) through at least one vapor-liquid separator, where the condensed tar separates from the gaseous effluent and the condensed tar is removed from the method as separator bottoms;
(c) cooling the tar-depleted gaseous effluent from step (b) in one or more cracked gas coolers to condense a liquid effluent quench oil;
(d) passing at least a portion of the effluent from step (c) containing liquid effluent quench oil through at least one rectifier comprising a fixed number of distillation stages ranging from about 2 to about 20 and/or equivalent suitable packing and comprising a reflux inlet for introducing a pyrolysis gasoline fraction, and further, obtaining liquid effluent quench oil as rectifier bottoms;
(e) cooling the gaseous effluent from step (d) to condense a liquid effluent comprising pyrolysis gasoline and water condensed from steam;
(f) treating a mixed gaseous and liquid effluent from step (e) to at least partially separate therefrom a liquid pyrolysis gasoline rich stream;
and
(g) passing at least a portion of the liquid pyrolysis gasoline rich stream as reflux to said rectifier.

5 more elements

Dependencies are inferred from the claim text.

Method for processing hydrocarbon pyrolysis effluent

Life of this patent

Method for processing hydrocarbon pyrolysis effluent

Life of this patent

Abstract

Claims23