Use of platforming process to isomerize light paraffins

Abstract

A process is presented for improving the feed to a cracking unit and a reforming unit from a naphtha feedstock. The process includes the use of a separation unit to generate a light naphtha feed and a heavy naphtha feed. The process further includes separating the light naphtha feed into a light naphtha feed comprising normal hydrocarbons and a light naphtha feed comprising non-normal hydrocarbons. The light naphtha feed comprising normal hydrocarbon is passed to the cracking unit and the heavy naphtha feed is passed to the reforming unit.

1 . A process for improved naphtha cracking and reforming, comprising:
 passing a naphtha feedstream to a naphtha splitter to generate a light naphtha and a heavy naphtha;   passing the light naphtha to a separation unit to generate an extract stream comprising normal hydrocarbons, and a raffinate stream comprising non-normal hydrocarbons;   passing the heavy naphtha to a reforming unit to generate a reformed effluent comprising aromatics, naphthenes and paraffins; and   passing the extract stream to a cracking unit to generate a light olefin stream.   
     
     
         2 . The process of  claim 1  wherein the separation unit is an adsorption-separation unit. 
     
     
         3 . The process of  claim 1  wherein the light naphtha comprises n-C6 and lighter hydrocarbons, and the heavy naphtha comprises C6 aromatics, cyclohexane and C7+ hydrocarbons. 
     
     
         4 . The process of  claim 1  wherein the light naphtha comprises iC6 and lighter hydrocarbons, and the heavy naphtha comprises C6 aromatics and C7+ hydrocarbons. 
     
     
         5 . The process of  claim 1  further comprising passing the reformed effluent to an aromatics extraction unit to generate an aromatics stream and an extraction raffinate stream comprising C5 and C6 paraffins. 
     
     
         6 . The process of  claim 5  further comprising passing the extraction raffinate stream to the cracking unit. 
     
     
         7 . The process of  claim 5  further comprising passing the aromatics stream to an aromatics complex. 
     
     
         8 . The process of  claim 2  wherein the adsorption separation unit uses a light desorbent having a boiling point lower than the lightest component in the feed. 
     
     
         9 . The process of  claim 8  wherein the light desorbent is normal butane, normal pentane, propane or ethane. 
     
     
         10 . The process of  claim 1  wherein the adsorption separation unit uses a heavy desorbent having a boiling point greater than the heaviest component in the feed. 
     
     
         11 . The process of  claim 10  wherein the heavy desorbent is normal heptane, normal octane, normal nonane, normal decane, normal undecane or normal dodecane. 
     
     
         12 . The process of  claim 1  further comprising passing the raffinate stream to the reforming unit. 
     
     
         13 . The process of  claim 1  further comprising passing the raffinate stream to an second fractionation column to generate a second overhead stream comprising iC5 and iC6, and a second bottoms stream comprising methyl cyclopentane, cyclohexane and benzene. 
     
     
         14 . The process of  claim 1  further comprising passing the raffinate stream to an second fractionation column to generate a second overhead stream comprising iC5, iC6, methyl cyclopentane, cyclohexane and benzene, and a second bottoms stream comprising cyclohexane and benzene. 
     
     
         15 . A process for improved light olefin yields from naphtha, comprising:
 passing a naphtha feedstream to a naphtha splitter to generate a light naphtha comprising C6 and lighter hydrocarbons and a heavy naphtha;   passing the light naphtha to an adsorption separation unit to generate an extract stream comprising normal hydrocarbons, and a raffinate stream comprising non-normal hydrocarbons;   passing the heavy naphtha to a reforming unit to generate a reformed effluent comprising aromatics;   passing the extract stream to a cracking unit to generate a light olefin stream; and   passing the heavy naphtha to the reforming unit to generate a reformate stream.   
     
     
         16 . The process of  claim 15  further comprising passing the reformate stream to an aromatics extraction unit to generate an aromatics stream and an extraction raffinate. 
     
     
         17 . The process of  claim 15  further comprising passing the raffinate stream to the reforming unit. 
     
     
         18 . The process of  claim 15  further comprising passing the raffinate stream to a fractionation unit to generate an overhead stream comprising isoparaffins having 5 and 6 carbons, and a bottoms stream comprising methyl cyclopentane, cyclohexane and benzene. 
     
     
         19 . The process of  claim 18  further comprising passing the bottoms stream to the reforming unit. 
     
     
         20 . The process of  claim 18  further comprising passing the overhead stream to a gasoline blending stock or to a reformer. 
     
     
         21 . The process of  claim 15  wherein the adsorption separation unit uses a light desorbent. 
     
     
         22 . The process of  claim 18  wherein the fractionation unit generates a bottoms stream, a side draw stream for passing to a gasoline blending stock, and an overhead stream for providing control over the Reid vapor pressure of the gasoline blending stock.