Targeted hydrogenation hydrocracking
First Claim
1. A method for hydroprocessing a hydrocarbon feedstock, said method employing multiple hydroprocessing zones within a single reaction loop, each zone having one or more catalyst beds, 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;
(b) passing the effluent of step (a) directly to a hot high pressure separator, wherein the effluent is separated to produce a vapor stream comprising hydrogen, hydrocarbonaceous compounds boiling at a temperature below the boiling range of the hydrocarbonaceous feedstock, hydrogen sulfide and ammonia and a liquid stream comprising hydrocarbonaceous compounds boiling approximately in the range of said hydrocarbonaceous feedstock;
(c) passing the vapor stream of step (b) after cooling and partial condensation, to a second hot high pressure separator where it is flashed, thereby producing an overhead vapor stream and a liquid stream, wherein the liquid stream, which comprises hydrotreated hydrocarbons in the middle distillate range, is passed to a second hydroprocessing zone;
(d) passing the overhead vapor stream from the hot high pressure separator of step (c), after cooling and contact with water, said vapor stream comprising hydrogen, ammonia, hydrogen sulfide, light gases and naphtha, to a cold high pressure separator, where hydrogen, hydrogen sulfide, and light hydrocarbonaceous gases are removed overhead, ammonia is removed from the cold high pressure separator as ammonium bisulfide in the sour water stripper, and naphtha and middle distillates are passed to fractionation;
(e) passing the liquid stream from the hot high pressure separator of step (b) to a hot low pressure separator, where it is flashed to produce an overhead stream comprising gases and a liquid stream comprising unconverted oil;
(f) passing the liquid stream of step (e) which comprises unconverted oil, to a steam stripper, where a vapor stream is removed overhead and a liquid stream, which comprises stripped unconverted oil, is recovered.
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Accused Products
Abstract
This invention is directed to a process scheme in which a partial conversion hydrocracking (HCR) unit, preferably preceded by a hydrotreating unit, feeds unconverted oil to a FCC (fluid catalytic cracking ) unit. Most refineries run the FCC unit at the full capacity for optimal asset utilization. During shutdowns of Residue Desulfurization unit(s) which feed an FCC unit, it is desirable to reduce the conversion in the FCC feed hydrocracker. In this way, the feed to FCC unit is maximized. Jet and Diesel products that conform to specifications may be produced during low conversion HCR operation. Furthermore, undesirable over-saturation of the unconverted oil (UCO) from the HCR unit feeding the FCC unit can be avoided. Excess hydrogen consumption can also be avoided. Normally, further aromatic saturation of the middle distillate products from a low conversion HCR is achieved in a separate, post treatment, unit.
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Citations
20 Claims
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1. A method for hydroprocessing a hydrocarbon feedstock, said method employing multiple hydroprocessing zones within a single reaction loop, each zone having one or more catalyst beds, comprising the following steps:
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(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; (b) passing the effluent of step (a) directly to a hot high pressure separator, wherein the effluent is separated to produce a vapor stream comprising hydrogen, hydrocarbonaceous compounds boiling at a temperature below the boiling range of the hydrocarbonaceous feedstock, hydrogen sulfide and ammonia and a liquid stream comprising hydrocarbonaceous compounds boiling approximately in the range of said hydrocarbonaceous feedstock; (c) passing the vapor stream of step (b) after cooling and partial condensation, to a second hot high pressure separator where it is flashed, thereby producing an overhead vapor stream and a liquid stream, wherein the liquid stream, which comprises hydrotreated hydrocarbons in the middle distillate range, is passed to a second hydroprocessing zone; (d) passing the overhead vapor stream from the hot high pressure separator of step (c), after cooling and contact with water, said vapor stream comprising hydrogen, ammonia, hydrogen sulfide, light gases and naphtha, to a cold high pressure separator, where hydrogen, hydrogen sulfide, and light hydrocarbonaceous gases are removed overhead, ammonia is removed from the cold high pressure separator as ammonium bisulfide in the sour water stripper, and naphtha and middle distillates are passed to fractionation; (e) passing the liquid stream from the hot high pressure separator of step (b) to a hot low pressure separator, where it is flashed to produce an overhead stream comprising gases and a liquid stream comprising unconverted oil; (f) passing the liquid stream of step (e) which comprises unconverted oil, to a steam stripper, where a vapor stream is removed overhead and a liquid stream, which comprises stripped unconverted oil, is recovered. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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9. The process of claim 9, wherein the hydroprocessing conditions of step 1(e) preferably comprise a temperature in the range from 650 m3 H2/m3 feed F.-850 m3 H2/m3 feed F. (343°
- C.-454°
C., reaction pressure in the range from 1500-3500 psig (10.4-24.2 MPa), LHSV in the range from 0.25 to 2.5 hr-1, and hydrogen consumption in the range from 500 to 2500 scf per barrel of liquid hydrocarbon feed (89.1-445 m3 H2/m3 feed).
- C.-454°
Specification