Fluidized bed coking with fuel gas production

Abstract

A Flexicoking™ unit which retains the capability of converting heavy oil feeds to lower boiling liquid hydrocarbon products while making a fuel gas from rejected coke to provide only a minimal coke yield. The heater section of the conventional three section unit (reactor, heater, gasifier) is eliminated and the cold coke from the reactor is passed directly to the gasifier which is modified by the installation of separators to remove coke particles from the product gas which is taken out of the gasifier for ultization. Hot coke from the gasifier is passed directly to the coking zone of the reactor to supply heat to support the endothermic cracking reactions and supply seed nuclei for the formation of coke in the reactor. Coke is withdrawn from the gasifier to remove excess coke and to purge the system of metals and ash.

Description

CROSS-REFERENCE TO RELATED APPLICATIONS[0001]This application claims priority to U.S. Provisional Application Ser. No. 62 / 014,762 filed Jun. 20, 2014, herein incorporated by reference in its entirety.FIELD OF THE INVENTION[0002]This invention relates to a fluid coking process in which a heavy oil feed is subjected to thermal cracking (coking) in a fluidized bed reactor with the coke product being converted by gasification to form a fuel gas.BACKGROUND OF THE INVENTION[0003]Heavy petroleum oils and residual fractions derived from them are characterized by a combination of properties which may be summarized as high initial boiling point, high molecular weight and low hydrogen content relative to lower boiling fractions such as naphtha, gasoline, and distillates; frequently these heavy oils and high boiling fractions exhibit high density (low API gravity), high viscosity, high carbon residue, high nitrogen content, high sulfur content, and high metals content.[0004]Technologies for upg...

AI Technical Summary

Benefits of technology

This patent describes a new way to make fuel from heavy oil that produces less coke and requires less equipment. This improvement involves eliminating a heater and using cyclones to separate coke particles from the fuel gas. The coke is then sent back to the reactor to support the cracking reactions and form coke seeds. The purged system is then used to make fuel.

Problems solved by technology

Carbon rejection processes generally operate at moderate to high temperatures and low pressures and suffer from a lower liquid yield of transportation fuels than hydrogen addition processes, because a large fraction of the feedstock is rejected as solid coke; light gases are also formed as by-products in the thermal cracking reactions and, being of high H / C ratio tend to degrade the quantity of the more valuable liquid products.

The liquids are generally of poor quality and must normally be hydrotreated before they can be used as feeds for catalytic processes to make transportation fuels.

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