Prerefining Process for the Hydrodesulfurization of Heavy Sour Crude Oils to Produce Sweeter Lighter Crudes Using Moving Catalyst System

Abstract

A pre-refining catalytic hydrotreating process for the desulfurization, demetallization, and upgrading of heavy, sour crude oils operating at a moderate temperature and pressure through the utilization of moving catalyst bed technology.

Description

RELATED APPLICATIONS[0001]This patent application claims priority to U.S. Provisional Patent Application Ser. No. 61 / 080,452 filed on Jul. 14, 2008, which is incorporated by reference in its entirety.TECHNICAL FIELD OF THE INVENTION[0002]The present invention relates to a pre-refining process for the upgrading of heavy sour crude oils using a catalytic hydrotreating process employing Hydrodemetallization (HDM), Hydrodesulfurization (HDS), and Hydroconversion (HDC), to produce sweeter, lighter crudes using a series of moving catalyst beds in discrete reactors.BACKGROUND OF THE INVENTION[0003]The removal of sulfur compounds from crude oil and its fractions has been of significant importance for several decades, but has become even more important in recent years due to tightening environmental legislation. While much of the prior art focuses on the desulfurization of individual crude oil fractions, a large segment of the art today and in the past has addressed the requirement for hydro...

AI Technical Summary

Benefits of technology

[0017]In a preferred embodiment, the HDM catalyst has a HDM catalyst flow rate, and the first effluent has a baseline effluent metal concentration, such that the process can include monitoring a metal concentration of the first effluent and increasing the HDM catalyst flow rate whenever the metal concentration of the first effluent exceeds the baseline effluent metal concentration. Likewise, the HDM / HDS catalyst can have an HDM / HDS catalyst flow rate, the second effluent can have a second baseline effluent metal concentration, and the second effluent can have a baseline sulfur concentration. Both a metal and a sulfur concentration of the second effluent can be monitored, and whenever the metal concentration of the second effluent exceeds the second baseline effluent metal concentration or whenever the sulfur concentration of the second effluent exceeds the baseline sulfur concentration, the HDM / HDS catalyst flow rate can be increased.

[0020]In another embodiment of the present invention, the third effluent is characterized as having a sulfur content of between about 0.1 and 1.0 weight percent. Additionally, the process can further include separating the whole crude oil feedstock into two fractions prior to introducing the heated-pressurized mixture into the HDM reaction zone. In this embodiment, the first fraction has a maximum boiling point of about 210° C., and the second fraction has a minimum boiling point of greater than about 210° C. Additionally, the first fraction can bypass said reaction zones and can be combined with the fourth effluent, wherein the second fraction is mixed with the hydrogen to form the heated-pressurized mixture.

Problems solved by technology

One of the major technical challenges posed when hydrotreating heavy oil fractions or whole crude is the effect of minor concentrations of contaminants such as organic nickel and vanadium compounds.

These organometallic components have been proven to detrimentally impact the activity of hydrotreating catalysts.

Another major challenge faced by processing whole crude oil is that the concentration of coke precursors can be very high.

These coke precursors, such as asphaltenic plates detrimentally impact the activity of the hydro-desulfurization (HDS) catalysts in question.

This means that the performance of a conventional process would decrease over time, requiring catalyst replacement to ensure continued operation.

This catalyst replacement can be both costly and time consuming, significantly impacting the economic feasibility of such a process.

These maxima limit the time for that a catalyst can operate without being replaced with fresh catalyst.

Furthermore, replacement of spent catalyst with fresh catalyst usually requires complete shutdown of the process unit in order to unload the deactivated spent catalyst and load a fresh batch of catalyst into the process.

This shutdown time reduces the on-stream time and therefore negatively impacts the economics of the process.

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