Alkali metal hydroprocessing of heavy oils with enhanced removal of coke products

摘要

Hydrocarbon feedstreams are desulfurized using an alkali metal reagent, optionally in the presence of hydrogen. Improved control over reaction conditions can be achieved in part by controlling the particle size of the alkali metal salt and by using multiple desulfurization reactors. The processes herein allow a simple and effective method for removing the majority of coke formed in the alkali metal reagent reactions with the hydrocarbon feedstreams. This makes it cost effective to run such processes at higher severities (which result in higher coke production) thereby resulting in increased amounts of valuable converted hydrocarbon product yields. The process improvements herein may also be used to increase total throughput through a unit due to the ability to effectively manage higher coke content in the reaction products.

主权项

1. A process for desulfurizing a hydrocarbon feedstream, comprising:
a) mixing at least a portion of a hydrocarbon feedstream having an API gravity of less than 19 with an aqueous alkali metal salt reagent solution to form a first mixed reactor feedstream; b) exposing at least a portion of the first mixed reactor feedstream to a first desulfurization reactor operated under first effective desulfurization conditions to form a first desulfurized reactor product stream comprising desulfurized oil, spent alkali metals, and coke; c) separating the first desulfurized reactor product stream to form at least a first low-boiling point vapor fraction and a first reactor product liquid fraction; d) mixing at least a portion of the first reactor product liquid fraction with water to form a first wash water separator feedstream; e) sending the first wash water separator feedstream to a first wash water separator vessel wherein in the first wash water separator vessel, the first wash water separator feedstream forms three distinct layers as flows: a first desulfurized oil product layer, a first emulsion phase layer, and a first aqueous spent alkali metal layer; f) removing each of the three distinct layers separately from the first wash water separator vessel to separately form a first desulfurized oil product stream, a first emulsion phase stream, and a first aqueous spent alkali metal stream; wherein at least 50 wt % of the total coke in the first desulfurized reactor product stream is removed in the first emulsion phase stream, and the first desulfurized oil product stream has a lower sulfur content by wt % than the hydrocarbon feedstream, and the first desulfurized oil product stream has a API gravity of at least 20 and a viscosity of less than or equal to 40 centistokes at 40° C.