Process for Removing a Contaminant from an Aromatic Selective Solvent
a technology of selective solvent and contaminant, which is applied in the direction of separation process, hydrocarbon distillation, chemistry apparatus and processes, etc., can solve the problems of contaminants entering the solvent, the solvent is more difficult to meet stringent purity and recovery requirements,
Inactive Publication Date: 2010-12-02
UOP LLC
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Benefits of technology
The invention is a process for removing a contaminant from an aromatic selective solvent. The process involves contacting a feed stream with the solvent in an extractive distillation zone to produce a raffinate stream with the non-aromatic hydrocarbon and a rich solvent stream with the aromatic hydrocarbon and the solvent. The rich solvent stream is then separated in a second distillation zone to produce an extract stream with the aromatic hydrocarbon and a lean solvent stream with the contaminant and a non-aromatic hydrocarbon. The lean solvent stream is then washed with a second non-aromatic hydrocarbon to produce a clean solvent stream with the aromatic selective solvent and a first by-product stream with the contaminant and the non-aromatic hydrocarbon. The clean solvent stream can be reused in the process. The process can also involve washing the first by-product stream with a second solvent to produce a second by-product stream with the contaminant and the non-aromatic hydrocarbon and an aqueous solvent stream with water and the aromatic selective solvent.
Problems solved by technology
Therefore, it can be more difficult to meet stringent purity and recovery requirements when the feed stream has a wider boiling range of mixed hydrocarbon species.
Contaminants may be introduced to the solvent via mechanical leaks in the equipment which could introduce items such as heating mediums or lubricating oils.
Method used
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[0032]This example is presented to further illustrate some aspects and benefits of the invention. The embodiments presented are not to be considered as limiting the scope of the invention. A computer simulation is performed using models that are developed and tested against laboratory washing, extraction, and separation procedures. To obtain a comparison against the prior art, this example assumes the lean solvent stream to be treated for contaminant removal in the lean solvent washing zone is the same as that defined in the Example which spans columns 10 and 11 of U.S. Pat. No. 3,642,614 ('614 Example). Although U.S. Pat. No. 3,642,614 includes additional process steps or unit operations such a liquid-liquid extractor and a liquid-liquid raffinate water wash column, these do not affect the comparison. A comparison of the lean washing step of the invention, using a counter-current extraction column as illustrated and described in FIG. 2A, to the contaminant (C9+ aromatics) removal i...
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Abstract
The invention is a process and apparatus for removing a contaminant from an aromatic selective solvent. A feed stream comprising an aromatic hydrocarbon and a non-aromatic hydrocarbon is contacted with the aromatic selective solvent in an extractive distillation zone to produce a raffinate stream comprising the non-aromatic hydrocarbon, and a rich solvent stream comprising the aromatic hydrocarbon and the solvent. The rich solvent stream is separated in a second distillation zone to produce an extract stream comprising the aromatic hydrocarbon, and a lean solvent stream comprising the contaminant and the aromatic selective solvent. At least a portion of the lean solvent stream is washed with a non-aromatic hydrocarbon to produce a clean solvent stream, at least a portion of which is passed to at least one of the extractive distillation zone and the second distillation zone.
Description
FIELD OF THE INVENTION[0001]This invention relates to apparatus and processes for separating aromatics from a mixture of hydrocarbon species via extractive distillation. More particularly, the invention relates to removing contaminants from the solvent used in such processes.BACKGROUND OF THE INVENTION[0002]Aromatic hydrocarbons, such as benzene, toluene, and xylene can be recovered from various hydrocarbon feed stocks including catalytic reformates, light by-products from various hydrocarbon process units such as xylene isomerization, by-product oil from the manufacture of coke, and hydrogenated pyrolysis gasolines that also contain non-aromatic hydrocarbons. Use of an aromatic selective solvent can facilitate the removal of the aromatic from non-aromatic hydrocarbons in, e.g., an extractive process. In some processes, the hydrocarbon feed stock can be contacted with an aromatic selective solvent, in an extractive distillation column (ED column), which may include the presence of w...
Claims
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IPC IPC(8): C10G7/00
CPCC10G21/16C10G21/28C10G21/22C10G21/20
Inventor NOE, JASON L.SULLIVAN, LAWRENCE E.BEADLE, BRUCE R.CASEY, EDWARD M.STOODT, THOMAS J.
Owner UOP LLC