Process for removing one or more sulfur compounds from a stream (UOP)

Process for removing one or more sulfur compounds from a stream (UOP)

Type	Patent
Inventor	Steven L. Krupa
Inventor	Cedric R. Freeman
URL	Free Full Text Source:  http://www.google.com/patents/US20140088334
Assignee	Uop Llc
Patent Number	US20140088334 A1
Issue Date	Mar 27, 2014
Abstract	One exemplary embodiment can be a process for removing one or more disulfide compounds from a caustic stream. The process can include passing the caustic stream, previously contacted with a hydrocarbon stream for removing one or more mercaptans, through a column to remove the one or more disulfide compounds downstream of a mercaptan oxidation zone. The caustic stream can be contacted with a solvent stream comprising one or more hydrocarbons in a column. The solvent stream can be passed to a plurality of beds for removal of extracted disulfides from the solvent over an adsorbent. DESCRIPTION OF THE RELATED ART A sulfur removal process can extract mercaptan from a hydrocarbon stream to a caustic stream. Subsequently, the caustic stream can be oxidized to convert the mercaptans to one or more disulfides. When disulfides form, the majority can separate from the caustic in the disulfide separator. As such, the caustic can be removed as a separate phase. Although at least a majority of the disulfide has been removed, some amount of disulfide can remain in the caustic that can be extracted back into the product hydrocarbon and contribute to the overall sulfur in a hydrocarbon product. Often to reduce the amount of disulfide in the caustic, a series of mixers and settlers can contact the caustic with a sulfur-free oil to remove the disulfide oil from the lean caustic. To attain lower levels of disulfide, additional mixers or settlers may be provided. Generally, minimizing additional mixer/settler combinations is desired due to the extra capital investment. As refiners and chemical manufacturers have to meet more stringent sulfur specifications, increased reduction in the disulfide amounts is desired. However, adding additional mixers and settlers can increase capital and operating costs. As a consequence, there is a desire to achieve the required specifications while minimizing costs. Moreover, accumulated disulfides from the lean caustic can accumulate in the hydrocarbon product, which may be subsequently removed by an adsorptive removal process that may add capital and utility cost to the project. Thus, any reduction of the amount of disulfide in the lean caustic can avoid the cost of subsequent removal in downstream treatment zones for the hydrocarbon product.