Fluid coking unit stripper

Abstract

An improved, fouling-resistant configuration for the stripper sheds of fluid coking units comprises an inverted, open-bottomed channel with apertures spaced along the length of the channel and spaced from the apex of the channel. Preferably, the channels are of an inverted-V configuration with a downwardly extending lip provided on each side of the channel, extending from the bottom edge of each side of the channel. The stripper sheds may be positioned parallel to one another in the stripper section of the reactor vessel or, alternatively, the sheds in different tiers in the stripper section may be disposed so that the longitudinal axes of the sheds are rotated angularly relative to the sheds in other rows.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application relates and claims priority to U.S. Provisional Patent Application Ser. No. 61 / 300,372, filed on Feb. 1, 2010 and U.S. Provisional Patent Application Ser. No. 61 / 280,625, filed on Nov. 6, 2009.FIELD OF THE INVENTION[0002]This invention relates to an improved stripper section for mitigating fouling and hydrocarbon carryunder in fluidized bed coking units.BACKGROUND OF THE INVENTION[0003]Fluidized bed coking (fluid coking) is a petroleum refining process in which heavy petroleum feeds, typically the non-distillable residue (resid) from fractionation, are converted to lighter, more useful products by thermal decomposition (coking) at elevated reaction temperatures, typically about 480 to 590° C., (about 900 to 1100° F.). The process is carried out in a unit with a large reactor vessel containing hot coke particles which are maintained in the fluidized condition at the required reaction temperature with steam injected at the ...

AI Technical Summary

Benefits of technology

[0010]In spite of these efforts, an improved stripper shed configuration would be desirable, combining the att

Problems solved by technology

During the contacting of the feed with the fluidized bed, some coke particles may become unevenly or too heavily coated with feed and during collision with other coke particles may stick together.

These heavier coke particles may not be efficiently fluidized by the steam injected into the bottom of stripper section so that they subsequently pass downwards from the reactor section into the stripper section where they may adhere to and build up on the sheds in the stripper section, mainly on the uppermost rows of sheds.

Accumulation of deposits on the stripper sheds can become so severe due to growth of the deposits into the open area between the sheds on the row above as to restrict fluidization of the coke in the reactor section and eventually shut the unit down.

As this material progresses through the stripper, additional cracking reactions occur.

With basic fluid cokers, unlike Flexicokers, this phenomenon is not greatly disadvantageous as the quantities are small but in the case of Flexicokers, this material is sent to the heater, where it is exposed to a high temperature, oxy

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