Alkaline solution contact process and apparatus relating thereto

Abstract

One exemplary embodiment can be a process for contacting an alkaline solution with kerosene or diesel. The process can include providing a stream of kerosene or diesel and at least one of a naphthenic acid and a salt thereof, with an additional alkaline solution to a prewash vessel, forming an emulsion interface between a kerosene or diesel phase and an alkaline phase in the prewash vessel, controlling an amount of the emulsion interface by withdrawing at least a portion of the emulsion interface between the two phases, and adding an acid to a withdrawn emulsion.

Description

FIELD OF THE INVENTION[0001]This invention generally relates to a process for contacting an alkaline solution with kerosene or diesel.DESCRIPTION OF THE RELATED ART[0002]Generally, a hydrocarbon feed, such as kerosene or diesel, is treated, and accompanying acidic components removed or reduced, in a prewash zone which is upstream of a mercaptan oxidation reactor vessel, a water wash column, a salt filter vessel, and a clay filter vessel for sweetening the hydrocarbon feed. Such vessels can be disclosed in, e.g., U.S. Pat. No. 7,223,332.[0003]As the quality of crude oil decreases and refiners move to processing lower quality hydrocarbon feedstocks, the concentrations of naphthenic and other acids in kerosene, diesel and other hydrocarbon cuts may increase. This increased acidic concentration can express itself, with a kerosene feed for example, as Total Acid Numbers (hereinafter may be referred to as “TAN”) of above 0.15 mg caustic consumed / gram kerosene. In some instances, refining ...

AI Technical Summary

Benefits of technology

The patent describes a way to treat hydrocarbon streams like diesel or kerosene to remove harmful acidic components. By using an alkaline solution, the method can make the hydrocarbon stream safer and of higher quality. This can improve the efficiency and cost-effectiveness of the process, and even allow for the purification of a wider range of hydrocarbon feeds. The technique can also reduce the volume of waste and the strength of the caustic used.

Problems solved by technology

In some instances, refining operations have observed TAN numbers of up to 0.45 in the field, which can result in greater corrosion within the crude refinery.

Such catalysts often have an activated carbon base that may be susceptible to deactivation by plugging of the carbon pores by an acid salt formed by the reaction of the acid with strong caustic.

These acid salts such as sodium naphthenate can lead to increased water and caustic in the product, which can increase salt and clay consumption and potentially lead to product failing to meet specifications.

In the case of a feed with a high TAN with limited equipment or flexibility, such as insufficient control of the valves or caustic strength, the formed rag layer may grow in thickness and shorting of the ECP grids and potentially pass in the effluent from the ECP.

Emulsion formation after caustic treatment can be of concern because emulsion formation and accumulation can impede sweetening of the mercaptan in the downstream reactor by deactivating the catalyst in the reactor, increasing consumption of salt for drying and clay treatments, and possibly causing product to not meet specification.

Typically, water treatment plants have difficulty processing this heavy emulsion layer, resulting in a reduction in the processing capabilities that can ultimately cause complications with the entire refinery operation.

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