Recovery of hydrocarbon values from pyrolytic vapors

Abstract

A process for producing light aromatics, intermediate coal liquids, tar acids, and heavy hydrocarbons from pyrolytic vapors produced by the pyrolysis of coal is described herein. Such pyrolytic vapors are contacted with a quench liquid which comprises a hydrogen donor solvent to condense the pyrolytic vapors and form a liquid mixture which comprises pyrolytic condensate. The liquid mixture is separated by vacuum flashing into a vapor containing tar acids and a liquid mixture containing the quench liquid and condensate remainder. This liquid mixture is then heated to transfer hydrogen from the hydrogen donor solvent to the condensate remainder. The hydrogenated liquid mixture is then separated into a heavy hydrocarbon stream and a solvent mixture which contains the spent and unused hydrogen donor solvent. The vapor produced by the vacuum flashing is then condensed and separated into a liquid stream containing tar acids, and a tar acid raffinate. A mixture of the solvent mixture and the tar acid raffinate is separated into a liquid stream containing light aromatics, a stream containing intermediate coal liquids, and a stream containing two- and three-ring aromatics and the spent and unused hydrogen donor solvent. The latter stream is then hydrogenated with gaseous hydrogen to produce two- and three-ring hydroaromatics and a hydrogenated spent hydrogen donor solvent, both of which are operative for recycle as a quench liquid and subsequently as a hydrogen donor solvent in the process.