Synergism Between HDS and EDS

Extractive desulfurization (EDS) probably will be economically attractive as a stand-alone process in some refinery applications. However, it seems likely that many refineries also will look to employ a synergistic combination 

Process Type Capital Cost TIC, USS/barreEday Conversion Cost US /barrel 

Based on the complementary reactivity of AAT compounds towards oxidation and hydrogenation mentioned above, it seems probable that the EDS processes, when used as post- or pre-treatment in connection with existing conventional HDS processes, will achieve the objectives of lowest combined capital and conversion costs for ULSD production. Preliminary estimates indicate that conversion cost will be below what is expected for high-severity hydrodesulfiirization. 

Example Process Configuration Sulfur, wppm Feed/Process/Product Conversion Cost US /barrel  

Another symbiotic relationship may exist between EDS and HDS due to the production of high-sulfiir extract from the EDS processes. The byproduct EDS extract will have a content of 65—85% poly-aromatics and 3—15 w% sulfur, and it will typically represent 15—30% of the feedstock. When the feedstock is first processed by EDS, the feed designated for HDS therefore may only need to be a fraction of the original volume. The resulting EDS extract will require processing by medium- or high-severity HDS, but pretreatment will unload the HDS unit by a substantial fraction, and the extract may indeed be a preferred, higher value feed than the feedstock it substitutes. 

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