Multi-stage hydrocracker with kerosene recycle
OwnerH. Alex Yoon, Jay Parekh +1inventors
InventorsH. Alex Yoon, Jay Parekh, Arthur J. Dahlberg
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Abstract
This invention relates to a multi-stage process for hydroprocessing gas oils. Preferably, each stage possesses at least one hydrocracking zone. The second stage and any subsequent stages possess an environment having a low heteroatom content. Light products, such as naphtha, kerosene and diesel, may be recycled from fractionation (along with light products from other sources) to the second stage (or a subsequent stage) in order to produce a larger yield of lighter products, such as gas and naphtha. Subsequent zones are maintained at a lower pressure than that of the first zone, thereby reducing operating expenses.
Claims17
A method for hydroprocessing a hydrocarbon feedstock, the method employing multiple hydroprocessing zones within a single reaction loop and comprising the following steps:
- (a) passing a hydrocarbonaceous feedstock to a first hydroprocessing zone having one or more beds containing hydroprocessing catalyst, the hydroprocessing zone being maintained at hydroprocessing conditions, wherein the feedstock is contacted with catalyst and hydrogen to produce a vapor stream and a liquid stream as effluent;
- (b) removing the vapor stream of step (a), which comprises hydrogen, hydrogen sulfide and light hydrocarbonaceous gases overhead;
- (c) combining the liquid stream of step (b) with the liquid effluent from other hydroprocessing zones;
- (d) passing the liquid stream of step (c), which comprises hydrocarbonaceous compounds boiling in approximately the same range of the hydrocarbonaceous feedstock, to fractionation;
- (e) separating the liquid stream of step (d), in fractionation, into gas, naphtha, kerosene and diesel fractions, in addition to the bottoms fraction;
- (f) passing the bottoms fraction of step (e) to further processing or recycling to one or more of the other hydroprocessing zones of step (c);
- (g) passing one or more of the naphtha, kerosene and diesel fractions to further processing as products or recycling one or more of the fractions to one or more of the other hydroprocessing zones of step (c), the kerosene, naphtha or diesel fractions being in combination with kerosene, naphtha or diesel fractions from other sources, said hydroprocessing zone or zones being maintained at hydroprocessing conditions and at lower pressure than the first hydroprocessing zone, and possessing an environment substantially free of H2S, NH3, or other heteroatom contaminants;
- (h) passing the effluent of step (g) to fractionation;
- (i) recovering in fractionation an increased amount of gas and naphtha, and a decreased amount of kerosene, in the fractionation stage of step (h) than in the fractionation step of step (e).
Dependencies are inferred from the claim text.