Patent ID: 7247235

Claim:
A process for the hydrogenation of a petroleum fraction which comprises: a) co-current contacting the petroleum fraction in a first hydrotreating unit with a first hydrogen stream under hydrogenation reaction conditions to provide a partially treated first effluent containing a liquid component and a first vapor component; b) cooling the first effluent in a first heat exchange step; c) removing the first vapor component from the cooled first effluent in at least one liquid-vapor separation unit to provide a separation unit effluent containing substantially only liquid component; d) heating the separation unit effluent in a second heat exchange step to provide a heated liquid component; e) introducing the heated liquid component of step (d) into a second hydrotreating unit, wherein a major portion of the heated liquid component of step (d) is contacted with a second hydrogen stream in a counter-current manner in a first reaction zone under hydrogenation reaction conditions in the presence of a first hydrogenation catalyst in at least a first catalyst bed to provide a treated bottom effluent which exits the first reaction zone at a bottom end of the first reaction zone and a hydrogen-containing gaseous effluent which exits the first reaction zone at a top end of the first reaction zone, and wherein a minor portion of the heated liquid component of step (d) is contacted with the hydrogen-containing gaseous effluent in a co-current manner in a second reaction zone under hydrogenation reaction conditions in the presence of a second hydrogenation catalyst to provide a treated overhead effluent which exits the second reaction zone at a top end of the second reaction zone; f) combining the entire treated overhead effluent with the treated bottom effluent to provide a combined treated effluent; and g) removing a second vapor component from the combined effluent of the second hydrotreating unit to provide a product stream.