High Purity Heavy Normal Paraffins Utilizing Integrated Systems

Abstract

A process is presented for producing a purified normal paraffin product stream. The process includes passing a hydrocarbon stream having the desired normal paraffins to an adsorption separation system. A process stream generated from the separation system and having the normal paraffins is passed to an adsorption unit for the selective adsorption of aromatic compounds from the process stream, thereby producing a purified product.

Description

FIELD OF THE INVENTION[0001]The invention relates to adsorption separation processes. The invention is specifically directed at a process to improve the capacity and purity of normal paraffins.BACKGROUND OF THE INVENTION[0002]The separation of various substances through selective adsorption is an important process for producing pure substances. However, this generally is a batch process, but with the development of simulated moving bed (SMB) technology, the adsorption separation process can be operated on a continuous basis. For simulated moving bed technology, the process uses a multiport rotary valve to redirect flow lines in the process. The simulation of a moving adsorbent bed is described in U.S. Pat. No. 2,985,589 (Broughton et al.). In accomplishing this simulation, it is necessary to connect a feed stream to a series of beds in sequence, first to bed no. 1, then to bed no. 2, and so forth for numerous beds, the number of beds often being between 12 and 24. These beds may be ...

AI Technical Summary

Benefits of technology

[0006]The present invention improves the purity of a normal paraffin stream by selectively removing aromatic compounds from the extract stream. The process is for the production of a purified heavy normal paraffin. A hydrocarbon stream is passed to a prefractionation unit to separate out a selected range of hydrocarbons. The prefractionation unit generates a first stream comprising light ends, a second stream comprising heavy ends, and a third stream comprising hydrocarbons in the desired range. The third stream is passed to a hydroprocessing unit where under a hydrogen atmosphere, contaminants within the stream are hydrogenated and removed, creating an effluent stream having reduced contaminants. The effluent stream is processed in an adsorption separation unit, where an extract stream comprising normal paraffins is generated, and a raffinate stream comprising non-normal hydrocarbons is generated. The extract stream is passed to an aromatics adsorption unit to selectively remove aromatic compounds that remain in the extract stream. The aromatics adsorption unit creates a process stream with a reduced heavy aromatic concentration. The process stream is passed to a separation unit to remove residual desorbent and light aromatics. The desorbent and light aromatics are components left in the aromatics adsorption unit during the regeneration of the aromatics adsorbent.

Problems solved by technology

While the multiport rotary disc valve of Carson (U.S. Pat. No. 3,040,777) provided a satisfactory valve design for the simultaneous interconnection of two independent groups of conduits such that each conduit of the first group could be brought into individual communication with every conduit of the second group, it is not suitable when three groups of conduits must be simultaneously interconnected in the same manner.

Adsorption separation uses expensive equipment, and the equipment is not readily replaced to increase the production of a product stream.

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