KR102142606B1 - Use of platforming methods to isomerize hard paraffins - Google Patents

Abstract

In the present invention, a method is provided for improving the supply from a naphtha feedstock to a cracking unit and a reforming unit. The method includes the use of a separation unit to produce a light naphtha feed and a heavy naphtha feed. The method further comprises the step of 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 containing normal hydrocarbons is transferred to the cracking unit and the heavy naphta feed is transferred to the reforming unit.

Description

Use of platforming methods to isomerize hard paraffins

Priority Declaration

This application claims the priority of U.S. Patent Application No. 62/334,891, filed May 11, 2016, the contents of which are incorporated herein by reference in their entirety.

Technology field

The present invention relates to a method for producing light olefins from a naphtha feed stream and aromatics from a reformer. The invention also relates to an improved method for increasing the yield of light olefins.

Ethylene and propylene, light olefin hydrocarbons with 2 or 3 atoms per molecule, are important chemicals for use in the production of other useful materials such as polyethylene and polypropylene, respectively. Polyethylene and polypropylene are two of the most common plastics found today and have a wide range of uses both as material fabrication and as packaging material. Other uses for ethylene and propylene include the production of vinyl chloride, ethylene oxide, ethylbenzene and alcohol. Steam cracking or pyrolysis of hydrocarbons essentially produces everything from ethylene and propylene. Hydrocarbons used as feedstocks for the production of light olefins include carbon-based materials including natural gas, petroleum liquids, naphtha, and coal, recycled plastics or any organic materials.

Ethylene plants are a very complex combination of reaction and gas recovery systems. The feedstock is charged into the cracking zone in the presence of steam at thermal conditions effective to produce the pyrolysis reactor effluent gas mixture. The pyrolysis reactor effluent gas mixture is separated into stabilized and purified components through a series of cryogenic and conventional fractionation steps. Conventional ethylene separation compartments of an ethylene plant comprising both cryogenic and conventional fractionation steps for recovering ethylene products having an ethylene purity greater than 99.5% are described in V. Kaiser and M. Picciotti entitled "Better Ethylene Separation Unit". In the literature. This document is shown in Hydrocarbon Processing Magazine, November 1988, pages 57-61, incorporated herein by reference.

Methods are known for increasing the conversion of the proportion of products of ethylene production from zeolite cracking processes to produce more ethylene and propylene by disproportionation or metathesis of olefins. Such a process is disclosed in US 5,026,935 and US 5,026,936, where the metathesis reaction step is used in combination with a contact cracking step to produce more ethylene and propylene by metathesis of C ₄ and heavier molecules. The catalytic cracking step uses a zeolite catalyst to convert a hydrocarbon stream having 4 or more carbon atoms per molecule to produce olefins with fewer carbon atoms per molecule. The hydrocarbon feedstream to the zeolite catalyst typically contains a mixture of 40% to 95% by weight of paraffins having 4 or more carbon atoms per molecule and 5% to 60% by weight of olefins having 4 or more carbon atoms per molecule. . In US 5,043,522, it is disclosed that the preferred catalyst for this zeolite cracking process is an acid zeolite, examples of which include several ZSM type zeolites or borosilicates. Of the ZSM-type zeolites, ZSM-5 is preferred. Other zeolites containing materials that can be used in the cracking process for producing ethylene and propylene are zeolite A, zeolite X, zeolite Y, zeolite ZK-5, zeolite ZK-4, synthetic mordenite, dealuminized mode It has been disclosed to include knights, and also naturally occurring zeolites including chabazite, sporesite, mordenite, and the like. Zeolites ion-exchanged to replace the alkali metal present in the zeolite are preferred. Preferred cation exchange cations are hydrogen, ammonium, rare earth metals and mixtures thereof.

In European Patent No. 109,059B1, 4 to 12 per molecule by contacting the feedstream with a ZSM-5 or ZSM-11 zeolite having a silica to alumina atomic ratio of 300 or less at a temperature of 400°C to 600°C. A method for the conversion of a feedstream comprising olefins with carbon atoms to propylene is disclosed. ZSM-5 or ZSM-11 zeolites are exchanged for hydrogen or ammonium cations. The reference also discloses that conversion to propylene is improved due to the recycling of any olefin having less than 4 carbon atoms per molecule, but unreacted paraffin tends to accumulate in the recycle stream. The reference provides an additional oligomerization step that facilitates the removal of paraffins, such as butane and especially isobutane, where olefins with 4 carbon atoms are oligomerized and are difficult to separate from C ₄ olefins by conventional fractionation. In the relevant European patent 109060B1, a process for the conversion of butene to propylene is disclosed. The process includes contacting butene with a zeolite compound selected from the group consisting of silicalite, borite, chromosilicate, and zeolite ZSM-5 and ZSM-11 having a silica to alumina molar ratio of 350 or more. The conversion is carried out at a temperature of 500°C to 600°C and a space velocity of 5 to 200 kg/hr per kg of pure zeolite compound. European Patent No. 109060B1 discloses the use of silicalite-1 in ion-exchanged, immersed or co-precipitated form using a modifying element selected from the group consisting of chromium, magnesium, calcium, strontium and barium. .

In general, heavier olefins with 6 or more carbon atoms per molecule produced in commercial ethylene plants are useful for the production of aromatic hydrocarbons. Some of the olefin products include olefins with 4 carbons per molecule. Some of these include both mono- and di-olefins and some paraffins, which include butane and iso-butane. Because the part with 4 carbon atoms per molecule is generally less valuable and requires significant processing to separate the di-olefin from the mono-olefin, the process improves the use of this part of the ethylene plant product and improves the ethylene and propylene Try to improve overall yield.

In naphtha cracking, it is difficult to obtain high selectivity for ethylene and propylene while maintaining high conversion. Therefore, improvements in catalysts and methods to achieve this are desired.

The present invention provides a method for improving the yield of light olefins.

A first embodiment of the present invention is a method for improved naphtha cracking and reforming, comprising: transferring a naphtha feedstream to a naphtha splitter to produce hard naphtha and heavy naphtha; Transferring the light naphtha to a separation unit to produce an extract stream comprising normal hydrocarbons and a raffinate stream comprising non-normal hydrocarbons; Transferring the heavy naphtha to a reforming unit to produce a modified effluent comprising aromatics, naphthene and paraffin; And transferring the extract stream to a cracking unit to produce a light olefin stream. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, wherein the separation unit is an adsorption-separation unit. One embodiment of the present invention, wherein the light naphtha comprises n-C6, methylcyclopentane and lighter hydrocarbons, and the heavy naphtha comprises C6 aromatics, cyclohexane and C7+ hydrocarbons. One, several, or all of the previous embodiments of this paragraph up to the embodiment. One embodiment of the present invention is that prior to this paragraph up to the first embodiment of this paragraph, wherein the light naphtha comprises iC6 and lighter hydrocarbons, and the heavy naphtha comprises C6 aromatics and C7+ hydrocarbons. One, several, or all of the embodiments. One embodiment of the present invention further comprises the step of transferring the modified effluent to the aromatics extraction unit to generate an aromatics stream and an aromatics extract raffinate stream comprising C5 and C6 paraffins. One, several, or all of the previous embodiments of this paragraph up to the first embodiment. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the step of conveying the aromatics extracted raffinate stream to the cracking unit. . One embodiment of the present invention further comprises the step of transferring the aromatics stream to the aromatics complex, one, several, or several of the previous embodiments of this paragraph up to the first embodiment of this paragraph. It is all. One embodiment of the present invention to the first embodiment of this paragraph, up to the first embodiment of this paragraph, wherein one embodiment of the present invention is that the adsorptive separation unit uses a lighter desorbent having a lower boiling point than the lightest component of the feed. One, several or all. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, wherein the hard desorbent is normal butane, normal pentane, propane or ethane. One embodiment of the present invention, up to the first embodiment of this paragraph, wherein the adsorptive separation unit uses a heavy desorbent having a higher boiling point than the heaviest component of the feed. One, several or all. One embodiment of the present invention is one of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the heavy desorbent is normal heptane, normal octane, normal normal, normal decane, normal undecane or normal dodecane. It is, some or all. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the step of transferring the raffinate stream to the reforming unit. In one embodiment of the present invention, some or all of the raffinate stream is transferred to a second fractionation column to provide a second overhead stream comprising iC5 and iC6 and a second bottom comprising methyl cyclopentane, cyclohexane and benzene. One, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising generating a stream. In one embodiment of the present invention, the raffinate stream is transferred to a second fractionation column to provide a second overhead stream comprising iC5, iC6, methyl cyclopentane, cyclohexane and benzene and a second bottom comprising cyclohexane and benzene. One, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising generating a sub-stream.

A second embodiment of the present invention is a method for improved naphtha-derived light olefin yield comprising transferring a naphtha feedstream to a naphtha splitter to produce light naphtha and heavy naphtha comprising C6 and lighter hydrocarbons; Transferring the light naphtha to an adsorptive separation unit to produce an extract stream comprising normal hydrocarbons and a raffinate stream comprising non-normal hydrocarbons; Transferring the heavy naphtha to a reforming unit to produce a modified effluent comprising aromatics; Transferring the extract stream to a cracking unit to produce a light olefin stream; And transferring the heavy naphtha to a reforming unit to produce a reformate stream comprising aromatics. One embodiment of the present invention further comprises transferring the aromatics stream to an aromatics extraction unit to produce an aromatics stream and extract raffinate, prior to the second paragraph of this paragraph until the second embodiment of this paragraph. One, several, or all of the embodiments. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph, further comprising the step of transferring the raffinate stream to the reforming unit. One embodiment of the present invention sends a raffinate stream to a fractionation unit to produce an overhead stream comprising isoparaffins having 5 and 6 carbons and a bottom stream comprising methyl cyclopentane, cyclohexane and benzene. One, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph, further comprising the steps of: One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph, further comprising the step of conveying the bottoms stream to the reforming unit. One embodiment of the present invention further comprises the step of transferring the overhead stream to a gasoline blending stock or to a reformer, one, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph. to be. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph, wherein the adsorptive separation unit uses a hard desorbent. One embodiment of the present invention is that the fractionation unit produces a bottoms stream, a side draw stream for transport to the gasoline blending stock and an overhead stream to provide control over the lead vapor pressure of the gasoline blending stock, One, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph.

Other objects, advantages and applications of the present invention will become apparent to those skilled in the art from the following detailed description and drawings.

1 is a diagram of a method of improving the quality of a feed to a cracking unit and a reforming unit.

The present invention relates to a method that improves flexibility in the operation of a refinery and allows the refiner to shift products easily with minimal additional equipment. The operation of new and existing equipment enables shifting of manufacturing to increase higher value products as the market shifts. Market shifting includes the need for different products such as raw materials, or prices of oils, and precursor materials for plastics such as aromatics or light olefins, or increased production of gasoline blending streams. The conventional processing of the naphtha feedstream is to use only naphtha splitters that are classified according to the boiling range. However, the boiling points of different hydrocarbons overlap considerably, where the operation of the cracking unit is most efficiently run on normal hydrocarbons, and the reforming unit is more efficient for heavier hydrocarbons and aromatic precursors such as methylcyclohexane and cyclohexane. Is performed. It is also advantageous to remove the normal C5 and C6 hydrocarbons from the feed to the reforming unit.

The present invention can increase the normal hydrocarbon content to be transported to the cracking unit, while separating the desired aromatics to be transported to the reforming unit.

In the naphtha complex, the feed properties for the reforming and steam cracking units have a large impact on the overall yield and efficiency of the complex. Due to similar boiling points, it is not possible to direct the correct molecule to the optimal processing unit, which leads to inefficiencies and overall lower profitability. One specific task is that n-hexane, which is preferred for steam crackers, has a very similar boiling point for benzene precursors (methylcyclohexane and cyclohexane) which are preferred for reforming units.

Instead of using only fractionation, another technique such as adsorption or a series of fractionation columns can be used to separate n-hexane prior to the fractionation unit so that it can be sent directly to a steam cracker. For this reason, UOP developed the LD MaxEne process. LD MaxEne has the added advantage of producing an iso-paraffin rich raffinate stream that can be used for gasoline blending which eliminates the need for isomerization units. Additionally, the need for iso-paraffins is limited for gasoline purposes due to restrictions imposed by regulations governing lead vapor pressure in gasoline. This is improved by using light iso-paraffins, such as isobutane and isopentane, as a process to convert n-paraffins.

The present invention is a method of improving the feed to a naphtha cracking unit and a reforming unit, thereby increasing the efficiency and yield of the naphtha cracking unit and reforming unit. As shown in FIG. 1, the method includes transferring the naphtha feedstream 8 to a naphtha splitter 10 to produce a hard naphtha 12 and a heavy naphtha 14. The light naphtha 12 is sent to a separation unit 20 to produce an extract stream 22 and a raffinate stream 24. The extract stream 22 contains normal hydrocarbons, and the raffinate stream 24 contains non-normal hydrocarbons. Heavy naphtha 14 is sent to reforming unit 30 to produce a reformed effluent stream 32 comprising aromatics naphthene and paraffin. Extract stream 22 may be transferred to cracking unit 40 to produce light olefin stream 42.

The method can further include transferring the modified effluent stream 32 to the aromatics extraction unit 50 to produce an aromatics stream 52 and an extract raffinate stream 54. The extracted raffinate stream 54 includes C5 and C6 paraffins, in particular normal C5 and C6 paraffins. The aromatics stream 52 can be transferred to the aromatics complex 60. In one embodiment, extract raffinate stream 54 is sent to cracking unit 40. In another embodiment, the extracted raffinate stream 54 is sent to an adsorptive separation unit 20. When the raffinate stream 54 is transferred to the separation unit 20, it is first hydrotreated, or it is transferred to the hydrotreatment unit 80 before being transferred to the separation unit 20. Hydrotreating unit 80 may be used to hydrogenate olefins or to remove any sulfur obtained from aromatics recovery unit 50.

In one particular embodiment, the separation unit 20 comprises an adsorption-separation unit comprising an adsorbent for preferentially adsorbing normal hydrocarbons to produce an extract stream 22 comprising a normal hydrocarbon and a raffinate stream 24. do.

In one embodiment, the light naphtha 12 comprises n-C6 and lighter hydrocarbons, and the heavy naphtha 14 comprises C6 aromatics, cyclohexane, and C7+ hydrocarbons. The naphtha splitter 12 may have altered operating conditions to shift the separation, or split, of the naphtha feedstream 8. In one operation, the naphtha splitter 10 is operated to produce light naphtha 12 comprising iC6 and lighter hydrocarbons and heavy naphtha 14 comprising C6 aromatics and C7+ hydrocarbons.

When the separation unit 20 is an adsorption-separation unit, the adsorption-separation unit may use a light desorbent or a heavy desorbent. For the light desorbent, the light desorbent is selected to have a lower boiling point than the lightest component of the feed to the adsorption-separation unit 20. For naphtha feedstreams that divide hard naphtha and heavy naphtha, the desorbent has a lower boiling point than the hardest component of the hard naphtha. Preferred desorbents for hard desorbents include normal butane, normal pentane, propane, or ethane, or even mixtures of hard normal paraffins.

For heavy desorbents, the heavy desorbents are selected to have a higher boiling point than the heaviest component of the light naphtha feed to the adsorption-separation unit 20. Preferred desorbents for heavy desorbents include normal heptane, normal octane, normal nonane, normal decane, normal undecane or normal dodecane, or even mixtures of heavy normal paraffins.

The process may further include transferring the raffinate stream 24 to the reforming unit 30. The raffinate stream 24 may contain lighter hydrocarbons such as iC4, iC5 and iC6, while the reforming unit 30 will isomerize a portion of the lighter hydrocarbons to normal hydrocarbons, the normal hydrocarbon cracking Can be sent to units. By separating the light iso-paraffins from the normal paraffins in the light naphtha stream 12, it is possible to improve the quality of the feed to the cracking unit and thereby improve the operating parameters.

In one embodiment, raffinate stream 24 is sent to a second fractionation column 70. The second fractionation column 70 may be a fractionation column for generating the second overhead stream 72 and the second bottom stream 74. The second fractionation column can be operated to produce a second overhead stream 72 comprising iC5 and iC6 hydrocarbons and a second bottoms stream with methyl cyclopentane, cyclohexane and benzene.

In an alternative operation, the second fractionation column 70 can be operated to send a portion of methyl cyclopentane and cyclohexane and benzene into the second overhead stream 72, the second bottom stream ( 74) cyclohexane and benzene. In one embodiment, the second bottoms stream 74 can be sent to a reforming unit 30.

In one alternative embodiment, the method is for light olefin yield from an improved naphtha feedstream. The naphtha feedstream is sent to a naphtha splitter to produce a light naphtha stream and a heavy naphtha stream. The heavy naphtha stream is sent to a reforming unit, producing a reformate stream comprising aromatics. The light naphtha stream is sent to an adsorptive separation unit to produce an extract stream and a raffinate stream. The extract stream contains normal hydrocarbons and is sent to a cracking unit to produce light olefins. The cracking unit can be a steam cracking unit or a contact cracking unit.

In one embodiment, the raffinate stream is sent to a reforming unit. In the reforming unit, isoparaffins can be isomerized to normal paraffins, and the unaromatized paraffins can be recovered and recycled for transport to the cracking unit.

In another embodiment, the raffinate stream can be sent to a fractionation unit. The fractionation unit can generate an overhead stream, a bottom stream, and a side draw stream 76. In one embodiment, the fractionation column can be a partition wall column.

From the fractionation unit, the overhead stream can include isoparaffins having 5 and 6 carbon atoms, and the bottom stream can include methyl cyclopentane, cyclohexane and benzene. The overhead stream can be sent to a gasoline blending stock or to a reformer to isomerize isoparaffins into normal paraffins.

The fractionation unit can be operated to control the production of the side draw stream, where the side draw stream can be transferred to a gasoline blending stock. The overhead stream can be used to adjust the hydrocarbon composition of the gasoline blending stock to provide control over the lead vapor pressure.

The aromatics stream from the reforming unit can be transferred to an aromatics extraction unit to produce an aromatics product stream and an aromatics extraction raffinate. The aromatics extract raffinate can be transferred to an adsorptive separation column to separate normal paraffins from non-normal hydrocarbons.

While the present invention has been described as being considered to be presently preferred embodiments, it should be understood that the invention is not limited to the disclosed embodiments and is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

Specific embodiments

It is to be understood that although the following is described in connection with specific embodiments, these descriptions are for the purpose of description and are not intended to limit the scope of the above description and appended claims.

A first embodiment of the present invention is a method for improved naphtha cracking and reforming, comprising: transferring a naphtha feedstream to a naphtha splitter to produce hard naphtha and heavy naphtha; Transferring the light naphtha to a separation unit to produce an extract stream comprising normal hydrocarbons and a raffinate stream comprising non-normal hydrocarbons; Transferring the heavy naphtha to a reforming unit to produce a modified effluent comprising aromatics, naphthene and paraffin; And transferring the extract stream to a cracking unit to produce a light olefin stream. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, wherein the separation unit is an adsorption-separation unit. One embodiment of the present invention, until the first embodiment of this paragraph, wherein the light naphtha comprises n-C6 and lighter hydrocarbons, and the heavy naphtha comprises C6 aromatics, cyclohexane and C7+ hydrocarbons. Is one, several, or all of the previous embodiments. One embodiment of the present invention, the previous embodiment of this paragraph up to the first embodiment of this paragraph, wherein the light naphtha comprises iC6 and lighter hydrocarbons, and the heavy naphtha comprises C6 aromatics and C7+ hydrocarbons. Either, some or all. One embodiment of the present invention further comprises the step of transferring the modified effluent to the aromatics extraction unit to produce an aromatics stream and an extract raffinate stream comprising C5 and C6 paraffins. One, several, or all of the previous embodiments of this paragraph up to the embodiment. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the step of transferring the extract raffinate stream to the cracking unit. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the step of transferring the aromatics stream to the aromatics complex. One embodiment of the invention is that the adsorptive separation unit uses a hard desorbent having a lower boiling point than the hardest component of the feed. One, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, wherein the hard desorbent is normal butane, normal pentane, propane or ethane. One embodiment of the present invention, up to the first embodiment of this paragraph, wherein the adsorptive separation unit uses a heavy desorbent having a higher boiling point than the heaviest component of the feed. One, several or all. One embodiment of the present invention is one of the preceding embodiments of this paragraph up to the first embodiment of this paragraph, wherein the heavy desorbent is normal heptane, normal octane, normal normal, normal decane, normal undecane or normal dodecane. It is, some or all. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising the step of transferring the raffinate stream to the reforming unit. One embodiment of the present invention transfers the raffinate stream to a second fractionation column to produce a second overhead stream comprising iC5 and iC6 and a second bottom stream comprising methyl cyclopentane, cyclohexane and benzene. One, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising a step. In one embodiment of the present invention, the raffinate stream is transferred to a second fractionation column to provide a second overhead stream comprising iC5, iC6, methyl cyclopentane, cyclohexane and benzene and a second bottom comprising cyclohexane and benzene. One, several, or all of the previous embodiments of this paragraph up to the first embodiment of this paragraph, further comprising generating a sub-stream.

A second embodiment of the present invention is a method for improved naphtha-derived light olefin yield comprising transferring a naphtha feedstream to a naphtha splitter to produce light naphtha and heavy naphtha comprising C6 and lighter hydrocarbons; Transferring the light naphtha to an adsorptive separation unit to produce an extract stream comprising normal hydrocarbons and a raffinate stream comprising non-normal hydrocarbons; Transferring the heavy naphtha to a reforming unit to produce a modified effluent comprising aromatics; Transferring the extract stream to a cracking unit to produce a light olefin stream; And transferring the heavy naphtha to a reforming unit to produce a reformate stream. One embodiment of the present invention further comprises the step of transferring the reformate stream to an aromatics extraction unit to produce an aromatics stream and an extract raffinate, prior to the second paragraph of this paragraph until the second embodiment of this paragraph. One, several, or all of the embodiments. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph, further comprising the step of transferring the raffinate stream to the reforming unit. One embodiment of the present invention sends a raffinate stream to a fractionation unit to produce an overhead stream comprising isoparaffins having 5 and 6 carbons and a bottom stream comprising methyl cyclopentane, cyclohexane and benzene. One, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph, further comprising the steps of: One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph, further comprising the step of conveying the bottoms stream to the reforming unit. One embodiment of the present invention further comprises the step of transferring the overhead stream to a gasoline blending stock or to a reformer, one, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph. to be. One embodiment of the present invention is one, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph, wherein the adsorptive separation unit uses a hard desorbent. One embodiment of the present invention is that the fractionation unit produces a bottoms stream, a side draw stream for transport to the gasoline blending stock and an overhead stream to provide control over the lead vapor pressure of the gasoline blending stock, One, several, or all of the previous embodiments of this paragraph up to the second embodiment of this paragraph.

Without further finishing, using the above description, those skilled in the art can use the present invention to its fullest extent and easily identify the essential characteristics of the present invention, without departing from the spirit and scope of the present invention. It is believed that changes and modifications can be made and adjusted to various usages and conditions. Accordingly, the preferred specific embodiments described above are illustrative only and should be considered in no way limiting the rest of the disclosure, which covers various modifications and equivalent arrangements included within the scope of the appended claims. It is intended to.

In the above, all temperatures are stated in degrees Celsius, and all parts and percentages are by weight, unless otherwise indicated.

Claims (10)

Transferring the naphtha feedstream to a naphtha splitter to produce hard naphtha and heavy naphtha;
Transferring the light naphtha to a separation unit to produce an extract stream comprising normal hydrocarbons and a raffinate stream comprising non-normal hydrocarbons;
Transferring the heavy naphtha to a reforming unit to produce a modified effluent comprising aromatics, naphthene and paraffin;
Transferring the extract stream to a cracking unit to produce a light olefin stream;
Transferring the modified effluent to the aromatics extraction unit to produce an aromatics stream and an extract raffinate stream comprising C5 and C6 paraffins;
Transferring the extracted raffinate stream to the cracking unit;
Transferring the aromatics stream to the aromatics complex;
Transferring the raffinate stream to a second fractionation column to produce a second overhead stream comprising iC5 and iC6 and a second bottom stream comprising methyl cyclopentane, cyclohexane and benzene; And
Isomerizing isoparaffins into normal paraffins by transferring a second overhead stream to a reformer.
Improved naphtha cracking and modification method comprising a. The separation unit is an adsorption-separation unit using a desorbent of normal butane, normal pentane, propane, ethane, normal heptane, normal octane, normal nonan, normal decane, normal undecane, or normal dodecane. Way. The method of claim 1, wherein the light naphtha comprises n-C6 and lighter hydrocarbons and the heavy naphtha comprises C6 aromatics, cyclohexane and C7+ hydrocarbons. The method of claim 1, wherein the light naphtha comprises iC6 and lighter hydrocarbons and the heavy naphtha comprises C6 aromatics and C7+ hydrocarbons. delete delete delete The method of claim 1, further comprising conveying the raffinate stream to a reforming unit. delete Transferring the naphtha feedstream to a naphtha splitter to produce hard naphtha and heavy naphtha;
Transferring the light naphtha to a separation unit to produce an extract stream comprising normal hydrocarbons and a raffinate stream comprising non-normal hydrocarbons;
Transferring the heavy naphtha to a reforming unit to produce a modified effluent comprising aromatics, naphthene and paraffin;
Transferring the extract stream to a cracking unit to produce a light olefin stream;
Transferring the modified effluent to the aromatics extraction unit to produce an aromatics stream and an extract raffinate stream comprising C5 and C6 paraffins;
Transferring the extracted raffinate stream to the cracking unit;
Transferring the aromatics stream to the aromatics complex;
Transferring the raffinate stream to a second fractionation column to produce a second overhead stream comprising iC5, iC6, methyl cyclopentane, cyclohexane and benzene and a second bottom stream comprising cyclohexane and benzene; And
Isomerizing isoparaffins into normal paraffins by transferring a second overhead stream to a reformer.
Improved naphtha cracking and modification method comprising a.

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