Methods For Treating Vacuum Gas Oil (Vgo) And Apparatuses For The Same (United States Patent Application 20150184088 – UOP)

CATEGORY: VACUUM GAS OIL
Methods For Treating Vacuum Gas Oil (Vgo) And Apparatuses For The Same (United States Patent Application 20150184088 – UOP)
July 2, 2015
Abstract
Embodiments of apparatuses and methods for treating a vacuum gas oil (VGO) hydrotreating feed are provided. In one example, a method comprises contacting the VGO hydrotreating feed with a first hydrotreating catalyst in the presence of hydrogen at first hydroprocessing conditions effective to form a first hydrotreated effluent. The first hydrotreated effluent is separated to form a hydrotreated VGO-containing stream and a hydrotreated diesel-containing stream. The hydrotreated VGO-containing stream is stripped and fractionated to form a VGO product stream. The hydrotreated diesel-containing stream is combined with a hydrotreated diesel-, naphtha-containing stream to form a combined stream. The combined stream is stripped to form a diesel product stream.
more particularly relates to methods and apparatuses for hydrotreating a VGO hydrotreating feed that contains VGO and diesel range hydrocarbons and further treatment of the hydrotreated effluent to recover a VGO product and a relatively high cetane number diesel product.
BACKGROUND
[0002] Vacuum gas oil (VGO) is a hydrocarbon stream recovered from one or more petrochemical refinery unit operations typically as a side cut from a vacuum column, a crude column and/or a coker column and contains sulfur, nitrogen, and other impurities. VGO can include, for example, light vacuum gas oil, heavy vacuum gas oil, heavy coker gas oil, light coker gas oil, and/or heavy atmospheric gas oil. Prior to treating to upgrade the oil, VGO comprises a range of various hydrocarbons (e.g., paraffins, olefins, naphthenes, aromatics with various molecular weights) with different boiling points at atmospheric pressure including a VGO range hydrocarbon fraction and a diesel range hydrocarbon fraction. For example, untreated VGO (e.g., VGO feedstock for treating) can have an initial boiling point (IBP) of from 270 to 350.degree. C. and a final boiling point (FBP) of from 500 to 580.degree. C. in which the VGO range hydrocarbon fraction has an IBP of from 330 to 360.degree. C. and a FBP of from 500 to 580.degree. C. and the diesel range hydrocarbon fraction has an IBP of from 270 to 300.degree. C. and a FBP of from 360 to 400.degree. C.
[0003] To remove sulfur, nitrogen and the other impurities and to generally upgrade the oil, VGO is hydrotreated and fractionated to form various hydrotreated effluent product streams that include a VGO product draw stream and a diesel product draw stream. The hydrotreated effluent product stream(s) can then be further treated downstream, for example, by a catalytic cracking process to convert and/or further upgrade the stream(s) to higher value refinery products. Unfortunately, the diesel product draw stream from hydrotreating and fractionating is a relatively low value diesel product having a corresponding relatively low cetane number(s). In particular, a cetane number is a measure of the combustible quality of diesel fuel during compression ignition. Higher cetane numbers (e.g., 52 or greater) correspond to higher value diesel products than diesel products having lower cetane numbers. Additionally, during catalytic cracking process of hydrotreated VGO, the resulting diesel range hydrocarbons typically known as light cycle oil (LCO) are still of relatively low value.
[0004] Accordingly, it is desirable to provide apparatuses and methods for treating a VGO feed that comprises primarily VGO and diesel range hydrocarbons to recover a VGO product and a relatively high cetane number diesel product. Furthermore, other desirable features and characteristics of the present invention will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.
BRIEF SUMMARY
[0005] Apparatuses and methods for treating a vacuum gas oil (VGO) hydrotreating feed that comprises primarily VGO and diesel range hydrocarbons are provided herein. In accordance with an exemplary embodiment, a method for treating a VGO hydrotreating feed comprises the steps of contacting the VGO hydrotreating feed with a first hydrotreating catalyst in the presence of hydrogen at first hydroprocessing conditions effective to form a first hydrotreated effluent. The first hydrotreated effluent is separated to form a hydrotreated VGO-containing stream and a hydrotreated diesel-containing stream. The hydrotreated VGO-containing stream is stripped and fractionated to form a VGO product stream. The hydrotreated diesel-containing stream is combined with a hydrotreated diesel-, naphtha-containing stream to form a combined stream. The combined stream is stripped to form a diesel product stream.
[0006] In accordance with another exemplary embodiment, a method for treating a VGO hydrotreating feed that comprises primarily VGO and diesel range hydrocarbons is provided. The method comprises the steps of contacting the VGO hydrotreating feed with a first hydrotreating catalyst in the presence of hydrogen in a first hydrotreating reactor that is operating at first hydroprocessing conditions effective to form a first hydrotreated effluent. The first hydrotreated effluent is advanced to a hot separator to form a first gas stream that comprises H.sub.2, H.sub.2S, NH.sub.3, and C.sub.1-C.sub.4 hydrocarbons and a first liquid stream that comprises VGO and diesel range hydrocarbons. The first liquid stream is introduced to a hot flash drum to form a hydrotreated VGO-containing stream and a second gas stream that comprises diesel range hydrocarbons. The hydrotreated VGO-containing stream is stripped in a stripper to form a stripped hydrotreated VGO-containing stream. The stripped hydrotreated VGO-containing stream is fractionated in a fractionator to form a VGO product stream. The second gas stream is cooled and introduced to a cold flash drum to form a hydrotreated diesel-containing stream. The hydrotreated diesel-containing stream is advanced to a diesel hydrotreating and separation zone and combined with a hydrotreated diesel-, naphtha-containing stream to form a combined stream. The combined stream is stripped in the diesel hydrotreating and separation zone to form a diesel product stream.
[0007] In accordance with another exemplary embodiment, an apparatus for treating a VGO hydrotreating feed that comprises primarily VGO and diesel range hydrocarbons is provided. The apparatus comprises a VGO hydrotreating and separation zone that is configured to receive the VGO hydrotreating feed. The VGO hydrotreating and separation zone comprises a first hydrotreating reactor that is configured for contacting the VGO hydrotreating feed with a first hydrotreating catalyst in the presence of hydrogen effective to form a first hydrotreated effluent. A hot separator is in fluid communication with the first hydrotreating reactor and is configured to separate the first hydrotreated effluent into a first gas stream that comprises H.sub.2, H.sub.2S, NH.sub.3, and C.sub.1-C.sub.4 hydrocarbons and a first liquid stream that comprises VGO and diesel range hydrocarbons. A hot flash drum is in fluid communication with the hot separator and is configured to separate the first liquid stream into a hydrotreated VGO-containing stream and a second gas stream that comprises diesel range hydrocarbons. A first stripper is in fluid communication with the hot flash drum and is configured to strip the hydrotreated VGO-containing stream to form a stripped hydrotreated VGO-containing stream. A fractionator is in fluid communication with the first stripper and is configured to fractionate the stripped hydrotreated VGO-containing stream to form a VGO product stream. A cooler and a cold flash drum are in fluid communication with the hot flash drum and are cooperatively configured to cool and remove water from the second gas stream and to form a hydrotreated diesel-containing stream. A diesel hydrotreating and separation zone is in fluid communication with the VGO hydrotreating and separation zone and is configured to receive the hydrotreated diesel-containing stream and a diesel hydrotreating feed that comprises diesel and naphtha range hydrocarbons. The diesel hydrotreating and separation zone comprises a second hydrotreating reactor that is configured for contacting the diesel hydrotreating feed with a second hydrotreating catalyst in the presence of hydrogen effective to form a second hydrotreated effluent. A high pressure separator is in fluid communication with the second hydrotreating reactor and is configured to separate the second hydrotreated effluent into a third gas stream that comprises H.sub.2, H.sub.2S, and NH.sub.3 and a hydrotreated diesel-, naphtha-containing stream. The diesel hydrotreating and separation zone is further configured to combine the hydrotreated diesel-, naphtha-containing stream with the hydrotreated diesel-containing stream to form a combined stream. A second stripper is configured to receive and strip the combined stream to form a diesel product stream.
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