FIELD: petroleum processing. SUBSTANCE: hydrocarbon feedstock is combined with hot hydrogen-containing outlet stream returned from hydrocracking zone and resulting mix is fed into denitification and desulfurization reaction zone to produce hydrogen sulfide and ammonia in order to purify fresh feedstock. Resulting hot stream leaving above- named reaction zone is freed of hydrogen in stripping zone wherein essentially the same pressure as in hydrogenation treatment zone is maintained using hydrogen-enriched gas stream to produce (i) vapor stream containing hydrogen, hydrocarbons with boiling temperatures below temperature range of hydrocarbon feedstock, hydrogen sulfide, and ammonia and (ii) liquid hydrocarbon stream. At least part of the latter is passed to hydrocracking stage to produce hot outlet stream to be returned into hydrogenation treatment zone. EFFECT: increased yields if desired products. 10 cl, 1 dwg, 3 tbl
