CN117004436A - Adsorption separation method and separation system for full fraction naphtha - Google Patents

Abstract

The present disclosure relates to a method and a system for adsorption separation of full fraction naphtha, the method comprising: s1, enabling full fraction naphtha to enter a first rectifying device for first rectifying separation to obtain light naphtha and heavy naphtha; s2, enabling light naphtha to enter a first adsorption separation device for first adsorption separation to obtain a first extract and a first raffinate; enabling heavy naphtha to enter a second adsorption separation device for second adsorption separation to obtain a second extract and a second raffinate; s3, enabling at least part of the first extract and at least part of the second extract to enter a partition tower for second rectification separation to obtain a first light fraction, a middle fraction and a first heavy fraction; s4, returning at least part of the first heavy fraction to the first adsorption separation device as a first desorbent; at least a portion of the first light fraction is returned to the second adsorptive separation device as the second desorbent. Desorbent is obtained from naphtha feedstock, reducing desorbent input and reducing energy consumption for desorbent separation.

Description

Adsorption separation method and separation system for full fraction naphtha

Technical Field

The present disclosure relates to the technical field of separating normal paraffins from naphtha, and in particular, to an adsorption separation method and separation system for full fraction naphtha.

Background

Naphtha initially refers to the light fraction of crude oil between the temperature at which it begins to distill from atmospheric distillation (i.e., the initial point of distillation) and 200 ℃ (higher or lower temperatures can also be cut as desired) and is a mixture of various hydrocarbons including C4 to C11 normal paraffins, isoparaffins, naphthenes and aromatics. The hydrocarbon mixtures from this fraction of different sources are also known as naphthas, such as hydrocracked naphthas, coker naphthas, catalytically cracked naphthas or oilfield gas condensate. The content of each component in naphtha from different sources is different, wherein the mass fraction of normal alkane is generally in the range of 20-50%, and the mass fraction of non-normal hydrocarbon is in the range of 50-80%. Naphtha can be used as a feedstock for steam cracking to make ethylene, catalytic reforming to make aromatics, or for gasoline blending.

When used as a raw material for preparing ethylene by steam cracking, the composition of naphtha has important influence on key indexes such as yield, operation period and production cost of the cracking process. The normal alkane is a high-quality raw material for producing olefin, the isoparaffin is inferior, the cyclic structure of aromatic hydrocarbon is basically unchanged under the high-temperature cracking condition, and the normal alkane is easy to condense and coke, and is not suitable for being used as a cracking raw material. When used as a feedstock for a reformer, naphthenes are easily converted to aromatics, which are better feedstocks, while normal paraffins are relatively less easily converted to aromatics. When used in gasoline blending, branched, cyclic and aromatic paraffins have significantly higher octane numbers than Yu Zhenggou paraffins. Therefore, the separation of different components of naphtha can significantly improve its utility value, with the separation of normal paraffins being the most pronounced: the separated normal alkane has higher alkene yield when being used for steam cracking, the other non-normal alkane components have higher octane number, and the other non-normal alkane components have higher arene yield when being used for reforming.

There are a number of patents which disclose the separation of normal paraffins by adsorption. For example, a series of patents US4176053, US4210771, US4595490, US4709116, etc. describe the vapor phase adsorption of low octane n-paraffins by a 5A molecular sieve adsorbent and the recycle of n-paraffins from the adsorbent back to the isomerization reaction by a gas purge, the purge gas being predominantly hydrogen. CN1179410a describes the separation of normal paraffins in C5, C6 alkane isomerization products by pressure swing adsorption. The gas phase adsorption separation method is mainly applicable to systems with narrower distillate ranges and lower carbon numbers. CN1710030a discloses a method for separating full-fraction naphtha by gas phase adsorption, which is difficult to desorb normal paraffins with higher carbon number, so that nitrogen is required to purge the adsorption column at 400 ℃ during desorption.

For wider fractions, liquid phase adsorption separation is a more suitable method. Desorbent is required to be used in the liquid phase adsorption separation process, and the selection of desorbent has an important influence on separation performance. CN102811984a discloses a process for separating normal paraffins from full range naphtha by simulated moving bed adsorption, using C12 hydrocarbons as desorbent, which has the advantage that the desorbent is easily separated from the components in the feed, thereby reducing the energy consumption for the desorbent separation and recycle. However, in the technical scheme for large-scale industrial production, on the premise of meeting the separation requirement, the problems of large consumption of desorbent, large energy consumption requirement and the like exist. And desorbents are generally special chemicals, which are relatively high in value, and the high consumption of desorbents also increases the cost.

Disclosure of Invention

The object of the present disclosure is to provide a method and a system for adsorption separation of full range naphtha, which can obtain desorbent from naphtha raw material, reduce desorbent investment and reduce energy consumption for desorbent separation.

In order to achieve the above object, the present disclosure provides a method for adsorption separation of full range naphtha, comprising: s1, enabling full fraction naphtha to enter a first rectifying device for first rectifying separation to obtain light naphtha rich in C5-C6 materials and heavy naphtha rich in C8-C10 materials; s2, enabling the light naphtha to enter a first adsorption separation device for first adsorption separation to obtain a first extract and a first raffinate; enabling the heavy naphtha to enter a second adsorption separation device for second adsorption separation to obtain a second extract and a second raffinate; s3, enabling at least part of the first extract and at least part of the second extract to enter a partition tower for second rectification separation to obtain a first light fraction, a middle fraction and a first heavy fraction; s4, returning at least part of the first heavy fraction to the first adsorption separation device as a first desorbent; at least a portion of the first light fraction is returned to the second adsorptive separation device as a second desorbent.

Optionally, the content of normal paraffins in the full range naphtha is 20 to 50 wt.%; the distillation range cutting point of the light naphtha and the heavy naphtha is at any value between 60 ℃ and 95 ℃; preferably, the content of C5-C6 normal paraffins in the light naphtha is 20-55 wt%, and the content of C8-C10 normal paraffins in the heavy naphtha is 15-35 wt%; the content of the normal paraffins of C5 and below in the first light fraction is more than 90 weight percent; the content of the normal paraffins of C9 and above in the first heavy fraction is more than 90 weight percent.

Optionally, the method further comprises: at least part of the first raffinate enters a first raffinate rectifying tower to carry out third rectifying separation to obtain a second light fraction and a second heavy fraction; feeding at least part of the second raffinate into a second raffinate rectifying tower for fourth rectifying separation to obtain a third light fraction and a third heavy fraction; returning at least a portion of said second heavy fraction to said first adsorptive separation device also as said first desorbent; at least a portion of the third light fraction is also returned to the second adsorptive separation device as the second desorbent.

Optionally, in step S1, the operating conditions of the first rectification separation include: the pressure at the top of the tower is 0.2-0.6 MPa, preferably 0.3-0.5 MPa, and the temperature at the top of the tower is 50-125 ℃, preferably 70-110 ℃.

Optionally, in step S2, the first adsorption separation device and the second separation device are liquid phase simulated moving bed adsorption separation devices; the operating conditions of the first adsorptive separation and the second adsorptive separation each independently comprise: the operating temperature is 80-220 ℃, preferably 100-180 ℃; the operating pressure is 0.5 to 3.0MPa, preferably 0.8 to 2.5MPa.

Optionally, the adsorbents of the first and second adsorptive separation devices each independently comprise 80 to 98 wt% of an active component and 2 to 20 wt% of a binder; optionally, the active component comprises a type a molecular sieve; the binder is one or more selected from alumina, kaolin, bentonite and attapulgite.

Optionally, in step S3, the number of theoretical plates of the dividing wall column is 40 to 90; wherein the number of theoretical plates of the separation wall section is 25-45, the number of theoretical plates of the public rectifying section is 5-15, and the number of theoretical plates of the public stripping section is 10-30; the method further comprises the steps of: said at least a portion of the first extract and at least a portion of the second extract are fed from the same side of the divided wall column divided wall section; the feeding position of the partition tower raw material is the 10 th to 25 th theoretical plates in the direction from top to bottom of the partition section, and the middle distillate extraction position is the 5 th to 20 th theoretical plates in the direction from bottom to top of the partition section; optionally, the conditions of the second rectification separation include: the operation pressure of the bulkhead tower is 0.1-0.5 MPa; the reflux ratio of the top of the dividing wall tower is 1.5-4 by mass.

Optionally, the method further comprises: another portion of the first light fraction and/or another portion of the first heavy fraction from the divided wall column is sent to a cracker.

A second aspect of the present disclosure provides an adsorption separation system for full range naphtha, the system comprising: a first rectifying device, a first adsorption separation device, a second adsorption separation device, and a dividing wall column; the first rectifying device comprises a naphtha raw material inlet, a light naphtha outlet and a heavy naphtha outlet; the first adsorption separation device comprises a light naphtha inlet, a first extract outlet, a first raffinate outlet and a first desorbent inlet; the light naphtha inlet is communicated with a light naphtha outlet of the first rectifying device; the second adsorption separation device comprises a heavy naphtha inlet, a second extract outlet, a second raffinate outlet and a second desorbent inlet; the heavy naphtha inlet is communicated with a heavy naphtha outlet of the first rectifying device; the partition tower is provided with a first extraction liquid inlet, a second extraction liquid inlet, a first light fraction outlet, a middle fraction outlet and a first heavy fraction outlet; the first extraction liquid inlet is communicated with a first extraction liquid outlet of the first adsorption separation device, and the second extraction liquid inlet is communicated with a second extraction liquid outlet of the second adsorption separation device; the first light fraction outlet is communicated with a second desorbent inlet of the second adsorption separation device; the first heavy fraction outlet is in communication with a first desorbent inlet of the first adsorptive separation device.

Optionally, the system further comprises a first raffinate rectification column and a second raffinate rectification column; the first raffinate rectification column comprises a first raffinate inlet, a second light fraction outlet and a second heavy fraction outlet; the first raffinate inlet is in communication with a first raffinate outlet of the first adsorptive separation device, and the second heavies outlet is in communication with a first desorbent inlet of the first adsorptive separation device; the second raffinate rectification column comprises a second raffinate inlet, a third light fraction outlet and a third heavy fraction outlet; the second raffinate inlet is in communication with a second raffinate outlet of the second adsorptive separation device, and the third light ends outlet is in communication with a second desorbent inlet of the second adsorptive separation device.

Through the technical scheme, the invention provides an adsorption separation method and a separation system for full-fraction naphtha, wherein the full-fraction naphtha is separated into light naphtha rich in C5-C6 materials and heavy naphtha rich in C8-C10 materials, the light naphtha enters a first adsorption separation device and the heavy naphtha enters a second adsorption separation device to be respectively and further adsorbed and separated, the obtained first extract liquid rich in normal paraffins and the obtained second extract liquid rich in normal paraffins are subjected to rectification treatment by using a partition rectifying tower, multi-component separation among normal paraffins with different carbon numbers is realized, and the partition rectifying tower can obtain more types of components so that the energy-saving effect is remarkable; and then returning the n-alkanes (first light fraction) with carbon number five or below obtained at the upper part of the partition wall rectifying tower as a second desorbent to the second adsorption separation device, and returning the n-alkanes (first heavy fraction) with carbon number nine or above obtained at the bottom of the partition wall rectifying tower as a first desorbent to the first adsorption separation device, thereby realizing the purpose of using the material obtained by the fractionation of the naphtha raw material as the desorbent, improving the resource utilization effect, reducing the cost of the desorbent and reducing the energy consumption required for separating the desorbent.

Additional features and advantages of the present disclosure will be set forth in the detailed description which follows.

Drawings

The accompanying drawings are included to provide a further understanding of the disclosure, and are incorporated in and constitute a part of this specification, illustrate the disclosure and together with the description serve to explain, but do not limit the disclosure. In the drawings:

fig. 1 is a schematic flow diagram of an exemplary process for the adsorptive separation of full range naphtha as provided by the present disclosure.

Fig. 2 is a schematic flow diagram of an exemplary process for the adsorptive separation of full range naphtha as provided by the present disclosure.

Description of the reference numerals

01-full fraction naphtha, 02-desorbent, 03-desorbent, 10-rectifying column, 11-light naphtha, 12-heavy naphtha, 20-first adsorptive separation device, 21-first extract, 22-first raffinate, 26-product, 30-second adsorptive separation device, 31-second extract, 32-second raffinate, 36-product, 40-dividing wall rectifying column, 41-first light fraction, 42-first heavy fraction, 43-middle fraction, 44-first light fraction serving as a steam cracking raw material, 45-first heavy fraction serving as a steam cracking raw material, 50-rectifying column, 51-first raffinate, 52-desorbent, 60-rectifying column, 61-desorbent, 62-second raffinate

Detailed Description

Specific embodiments of the present disclosure are described in detail below with reference to the accompanying drawings. It should be understood that the detailed description and specific examples, while indicating and illustrating the disclosure, are not intended to limit the disclosure.

A first aspect of the present disclosure provides a process for the adsorptive separation of full range naphtha comprising the steps of:

s1, enabling full fraction naphtha to enter a first rectifying device for first rectifying separation to obtain light naphtha rich in C5-C6 materials and heavy naphtha rich in C8-C10 materials;

s2, enabling the light naphtha to enter a first adsorption separation device for first adsorption separation to obtain a first extract and a first raffinate; enabling the heavy naphtha to enter a second adsorption separation device for second adsorption separation to obtain a second extract and a second raffinate;

s3, enabling at least part of the first extract and at least part of the second extract to enter a partition tower for second rectification separation to obtain a first light fraction, a middle fraction and a first heavy fraction;

s4, returning at least part of the first heavy fraction to the first adsorption separation device as a first desorbent; at least a portion of the first light fraction is returned to the second adsorptive separation device as a second desorbent.

According to the method provided by the disclosure, full-fraction naphtha is separated into light naphtha rich in C5-C6 materials and heavy naphtha rich in C8-C10 materials, the light naphtha enters a first adsorption separation device and the heavy naphtha enters a second adsorption separation device to be respectively and further adsorbed and separated, the obtained first extract liquid rich in normal paraffins and the obtained second extract liquid rich in normal paraffins are subjected to rectification treatment by using a partition rectifying tower, multicomponent separation among normal paraffins with different carbon numbers is realized, and the partition rectifying tower can obtain more kinds of components, so that the energy-saving effect is remarkable; and then returning the n-alkanes (first light fraction) with carbon number five or below obtained at the upper part of the partition wall rectifying tower as a second desorbent to the second adsorption separation device, and returning the n-alkanes (first heavy fraction) with carbon number nine or above obtained at the bottom of the partition wall rectifying tower as a first desorbent to the first adsorption separation device, thereby realizing the purpose of using the material obtained by the fractionation of the naphtha raw material as the desorbent, improving the resource utilization effect, reducing the cost of the desorbent and reducing the energy consumption required for separating the desorbent.

In a preferred embodiment, the boiling range cut point of the light naphtha and the heavy naphtha is a temperature of any value between 60 and 95 ℃.

The method comprises the steps of cutting full-fraction naphtha into light naphtha rich in C5-C6 materials and heavy naphtha rich in C8-C10 materials according to the distillation range; the light naphtha contains a majority of normal paraffins which enter the first extraction liquid, the light naphtha contains a majority of non-normal paraffins which enter the first raffinate, and the normal paraffins are separated from the light naphtha and can be used as high-quality raw materials of a steam cracking device, and the non-normal paraffins separated from the light naphtha are high-octane components; the normal paraffins can be converted into high-octane components or non-normal paraffins can be converted into normal paraffins as required to be used as high-quality cracking raw materials. The majority of normal paraffins in the heavy naphtha enter the second extract, and the majority of non-normal paraffins in the heavy naphtha enter the second raffinate; the normal paraffins separated from the heavy naphtha can be used as a high-quality raw material of a steam cracking device, and the non-normal paraffins separated from the heavy naphtha are high-quality reforming raw materials. By utilizing the method provided by the disclosure, all components in the full fraction naphtha can be fully utilized according to the characteristics of the full fraction naphtha, and various different product requirements can be flexibly met.

In a specific embodiment, the content of C5-C6 normal paraffins in the light naphtha is 20-55 wt%, and the content of C8-C10 normal paraffins in the heavy naphtha is 15-35 wt%.

The full range naphtha in the present disclosure may be various naphthas, preferably one or a mixture of several of straight run naphthas, hydrocracked naphthas, coker naphthas, catalytically cracked naphthas and oilfield gas condensate.

In a preferred embodiment, the total fraction naphtha contains 20 to 50 wt.% of normal paraffins.

In one embodiment, the method further comprises:

at least part of the first raffinate enters a first raffinate rectifying tower to carry out third rectifying separation to obtain a second light fraction and a second heavy fraction; feeding at least part of the second raffinate into a second raffinate rectifying tower for fourth rectifying separation to obtain a third light fraction and a third heavy fraction;

returning at least a portion of said second heavy fraction to said first adsorptive separation device also as said first desorbent;

at least a portion of the third light fraction is also returned to the second adsorptive separation device as the second desorbent.

The first raffinate and the second raffinate containing non-normal paraffins are further rectified through the steps, and the second heavy fraction and the third light fraction which are suitable for full use are used as desorbents, so that the source of the desorbents is further expanded, the resource utilization effect is improved, and the investment of the desorbents is reduced.

The conditions for the third and fourth distillations in this disclosure are conventional in the art and may be adjusted according to the composition of the raw materials and the target separation effect. In an exemplary embodiment, the conditions of the third rectification separation and the fourth rectification separation may include: the pressure at the top of the tower is 0.12-0.2 MPa, and the reflux ratio is 0.3-1.0.

In one embodiment, in step S1, the operating conditions of the first rectification separation include: the pressure at the top of the tower is 0.2-0.6 MPa, preferably 0.3-0.5 MPa, and the temperature at the top of the tower is 50-125 ℃, preferably 70-110 ℃.

In one embodiment, in step S2, the first adsorption separation device and the second separation device are liquid phase simulated moving bed adsorption separation devices;

the operating conditions of the first adsorptive separation and the second adsorptive separation each independently comprise: the operating temperature is 80-220 ℃, preferably 100-180 ℃; the operating pressure is 0.5 to 3.0MPa, preferably 0.8 to 2.5MPa.

In a specific embodiment, the adsorbents of the first and second adsorptive separation devices each independently comprise 80 to 98% by weight of an active component and 2 to 20% by weight of a binder;

the active component comprises a type a molecular sieve;

the binder is one or more selected from alumina, kaolin, bentonite and attapulgite.

In a specific embodiment, the simulated moving adsorbent bed employs a device conventionally selected in the art, specifically comprising one or more adsorption towers, preferably one adsorption tower, each separated into a plurality of adsorption beds by a grid, the function of the grid being: redistributing the material from the previous bed to the next bed, uniformly mixing the externally introduced material with the material from the previous bed, and leading out part of the material from the previous bed from the adsorption tower. The grid allows the liquid to pass through and intercepts the sorbent particles from escaping the sorbent bed, and the upper and lower surfaces thereof typically employ wire mesh, metal sintered mesh or johnson mesh. The material introduced from the outside to a certain bed and the material led out of the adsorption tower from the previous bed all enter and are led out of the adsorption bed through the pipeline connected with the bed grid.

Specifically, the materials entering and exiting the adsorption tower at least comprise raw materials, desorbent, extracted liquid and raffinate. Wherein the raw material is naphtha, and the adsorbent has higher adsorption selectivity to normal paraffins in the raw material. The boiling points of the desorbent and the raw materials have great difference, the desorbent can be separated from the components in the raw materials through rectification, the material rich in C5-C6 alkane is treated by the first adsorption separation device, the material with C9 and above normal alkane or C10 and above normal alkane is adopted as the first desorbent, and the first desorbent can be obtained from the bottom of a partition tower for treating the effluent so as to supplement the first desorbent for the first adsorption separation device; the second adsorption separation device is used for treating the alkane material rich in C8 and above, and the normal alkane with C5 and below is used as a second desorbent, and the second desorbent can be obtained from the top of a partition tower for treating the effluent so as to supplement the second adsorption separation device with the second desorbent. The extraction liquid separated by the first adsorption separation device and the second adsorption separation device is enriched with n-alkane components which are preferentially adsorbed and also contains a part of desorbent; the raffinate contains a smaller amount of normal alkane, the smaller the content of the normal alkane is, the higher the adsorption separation efficiency is, and the main components of the raffinate are desorbent and non-normal alkane components in the raw material. And respectively introducing the raffinate obtained by the first adsorption separation device and the raffinate obtained by the second adsorption separation device into rectification towers (a first raffinate rectification tower and a second raffinate rectification tower), and separating desorbent contained in the two raffinate to be recycled. Wherein the first desorbent is separated from the bottom of the first raffinate rectification column and the second desorbent is separated from the top of the second raffinate rectification column.

In one embodiment, a part of the first extract liquid in the first adsorption separation device can be directly taken as the normal alkane product sending device without entering the partition rectifying tower, and the reduced circulating desorbent can be recovered and supplemented from the bottom of the partition rectifying tower, so that the energy consumption for separating the desorbent can be reduced. In one embodiment, a part of the second extract liquid in the second adsorption separation device can be directly taken as the normal alkane product sending device without entering the partition rectifying tower, and the reduced circulating desorbent can be recovered and supplemented from the top of the partition rectifying tower, so that the energy consumption for separating the desorbent is reduced.

In one embodiment, in step S3, the number of theoretical plates of the divided wall column is 40 to 90; wherein the number of theoretical plates of the separation wall section is 25-45, the number of theoretical plates of the public rectifying section is 5-15, and the number of theoretical plates of the public stripping section is 10-30; the method further comprises the steps of:

said at least a portion of the first extract and at least a portion of the second extract are fed from the same side of the divided wall column divided wall section; the feeding position of the raw materials of the partition tower is the 10 th to 25 th theoretical plates in the direction from top to bottom of the partition section, and the middle distillate extraction position is the 5 th to 20 th theoretical plates in the direction from bottom to top of the partition section.

In a preferred embodiment, the conditions of the second rectification separation include: the operation pressure of the bulkhead tower is 0.1-0.5 MPa; the reflux ratio of the top of the dividing wall tower is 1.5-4 by mass.

Specifically, all or part of the first extract and the second extract are fed from one side of a partition wall section of the partition wall tower, and the carbon six-carbon eight-normal alkane is extracted from the other side of the partition wall section; obtaining n-alkanes with carbon number of five or below at the top of a public rectifying section above a partition wall section of the partition wall tower; and obtaining more than nine n-alkanes at the bottom of the public stripping section below the partition wall section of the partition wall tower.

According to the present disclosure, a desorption zone, a purification zone, an adsorption zone, and an isolation zone are divided in an adsorption column along a material flow direction within the adsorption column. The adsorbent bed between desorbent injection and extraction liquid extraction is a desorption zone, the adsorbent bed between extraction liquid extraction and raw material injection is a purification zone, the adsorbent bed between raw material injection and raffinate extraction is an adsorption zone, and the adsorbent bed between raffinate extraction and desorbent injection forms an isolation zone. The number of simulated moving bed layers is 6 to 24, preferably 8 to 12.

In one embodiment, the method further comprises: another portion of the first light fraction and/or another portion of the first heavy fraction from the divided wall column is sent to a cracker.

A second aspect of the present disclosure provides an adsorption separation system for full range naphtha, the system comprising: a first rectifying device, a first adsorption separation device, a second adsorption separation device, and a dividing wall column; the first rectifying device comprises a naphtha raw material inlet, a light naphtha outlet and a heavy naphtha outlet;

the first adsorption separation device comprises a light naphtha inlet, a first extract outlet, a first raffinate outlet and a first desorbent inlet; the light naphtha inlet is communicated with a light naphtha outlet of the first rectifying device;

the second adsorption separation device comprises a heavy naphtha inlet, a second extract outlet, a second raffinate outlet and a second desorbent inlet; the heavy naphtha inlet is communicated with a heavy naphtha outlet of the first rectifying device;

the partition tower is provided with a first extraction liquid inlet, a second extraction liquid inlet, a first light fraction outlet, a middle fraction outlet and a first heavy fraction outlet; the first extraction liquid inlet is communicated with a first extraction liquid outlet of the first adsorption separation device, and the second extraction liquid inlet is communicated with a second extraction liquid outlet of the second adsorption separation device; the first light fraction outlet is communicated with a second desorbent inlet of the second adsorption separation device; the first heavy fraction outlet is in communication with a first desorbent inlet of the first adsorptive separation device.

In one embodiment, the system further comprises a first raffinate rectification column and a second raffinate rectification column;

the first raffinate rectification column comprises a first raffinate inlet, a second light fraction outlet and a second heavy fraction outlet; the first raffinate inlet is in communication with a first raffinate outlet of the first adsorptive separation device, and the second heavies outlet is in communication with a first desorbent inlet of the first adsorptive separation device;

the second raffinate rectification column comprises a second raffinate inlet, a third light fraction outlet and a third heavy fraction outlet; the second raffinate inlet is in communication with a second raffinate outlet of the second adsorptive separation device, and the third light ends outlet is in communication with a second desorbent inlet of the second adsorptive separation device.

Any device employed in the present disclosure is a structure conventionally selected in the art.

In a specific embodiment, referring to fig. 1, a specific process flow of the adsorption separation method of full fraction naphtha provided in the present disclosure includes the following steps:

the material 01 (full fraction naphtha) is subjected to first rectification separation by a rectification tower 10 (a first rectification device) to obtain a material 11 (light naphtha) and a material 12 (heavy naphtha); the material 11 is light naphtha fraction, and passes through the first adsorption separation device 20 to obtain a first extract 21 and a first raffinate 22, wherein all the first extract 21 can enter the partition wall rectifying tower 40, or a part of the first extract 21 can be separated and directly used as a product 26, and the rest part of the first extract enters the partition wall rectifying tower 40; the first raffinate enters a rectifying tower 50 (first raffinate rectifying tower), first raffinate oil 51 (second light fraction) is obtained by separating from the top of the rectifying tower 50, and desorbent 52 (second heavy fraction) is arranged at the bottom. The material 12 is heavy naphtha fraction, and passes through a second adsorption separation device 30 to obtain a second extract 31 and a second raffinate 32, wherein all the second extract 31 can enter a partition rectifying tower 40, or a part of the second extract 31 can be separated and directly used as a product 36, and the rest part of the second extract enters the partition rectifying tower 40; the second raffinate 32 enters a rectifying tower 60 (second raffinate rectifying tower), a desorbent 61 (third light fraction) is obtained by separating from the top of the rectifying tower 60, and a second raffinate oil 62 (third heavy fraction) is arranged at the bottom of the rectifying tower.

In the divided wall rectifying column 40, three materials are separated, a C5 and lower normal paraffins material 41 (first light fraction) is separated at the top of the divided wall rectifying column 40, a C9 and higher normal paraffins or a C10 and higher normal paraffins material 42 (first heavy fraction) is separated at the bottom of the divided wall rectifying column 40, and a material 43 (middle fraction) mainly containing C6 to C8 normal paraffins is obtained from the middle part of the divided wall rectifying column 40. At least a portion of the material 41 (first light fraction) merges with desorbent 61 (third light fraction) from the rectifying column 60 as second desorbent 03 of the second adsorptive separation device 30 and at least a portion of the material 42 (first heavy fraction) merges with desorbent 52 (second heavy fraction) from the rectifying column 50 as first desorbent 02 of the first adsorptive separation device 20.

The following examples will further illustrate the disclosure, but are not intended to limit the disclosure.

In the following examples, the adsorbent properties of the first and second adsorptive separation devices were referred to as RAN-520 adsorbent of south tokyo division of chinese petrochemical catalyst, inc, whose composition included an active component 5A molecular sieve (content > 90 wt%) with the remainder being binder kaolin.

Example 1

The method shown in fig. 2 is adopted, and specifically comprises the following steps:

in this example, full range naphtha was used as the feed at a flow rate of 100t/h. The naphtha composition is shown in Table 1 and includes C5 to C11 hydrocarbons with a n-alkane mass fraction of 28.7 wt.%.

The material 01 (full fraction naphtha) is subjected to first rectification separation in a rectifying tower 10 (a first separating device) to obtain a material 11 (light naphtha) mainly containing C5 and C6, wherein the C5 hydrocarbon accounts for 38.6 weight percent, the C6 hydrocarbon accounts for 58.3 weight percent, the normal alkane accounts for about 42.4 weight percent, and the content of C5-C6 normal alkane in the light naphtha is about 41.6 weight percent; the bottoms gave a feed 12 (heavy naphtha) containing C7 and above fractions, wherein the C5 to C6 hydrocarbons comprise 5.3 wt.% and the normal paraffins comprise 23.5 wt.% and the C8 to C10 normal paraffins in the heavy naphtha comprises about 15.6 wt.%. The distillation range of the light naphtha is 27.6-73.0 ℃, and the distillation range of the heavy naphtha is 85.5-169 ℃. Wherein the operating conditions of the first rectification separation include: the overhead pressure was 0.35MPa and the overhead temperature was 84 ℃.

The material 11 (light naphtha) is subjected to a first adsorptive separation by a first adsorptive separation unit 20 with C9 normal hydrocarbons as a first desorbent to produce a first extract 21 and a first raffinate 22. Wherein the operating conditions of the first adsorptive separation comprise: the operating temperature was 140℃and the operating pressure was 2.0MPa, and the feed rate of the liquid phase material in the first adsorption separation device was 27.5t/h. Wherein the first extract 21 is composed of C9 and above normal hydrocarbon desorbent and most normal alkane in C5 and C6 fractions, and all the first extract 21 enters the partition rectifying tower 40; a first raffinate 22 is obtained from the first adsorptive separation device 20, and comprises the C9 and above normal hydrocarbon desorbent and most of non-normal paraffins in the C5 and C6 fractions, the first raffinate 22 enters a rectifying tower 50 (first raffinate rectifying tower) for third rectifying separation, the C9 and above normal hydrocarbon desorbent and the C5 and C6 fractions of non-normal paraffins are separated, and the C9 and above normal hydrocarbon desorbent 52 (second heavy fraction) is recycled to the first adsorptive separation device 20, and the C5 and C6 fractions of non-normal paraffins 51 (second light fraction) are obtained as products and can be used as high-octane gasoline blending components.

The feed 12 (heavy naphtha) is sent to a second adsorptive separation unit 30 for a second adsorptive separation with C5 normal hydrocarbons as a second desorbent to produce a second extract 31 and a second raffinate 32. Wherein the operating conditions of the second adsorptive separation comprise: the operating temperature is 120 ℃, the operating pressure is 2.0MPa, and the flow rate of the liquid phase material in the second adsorption separation device is 72.5t/h. Wherein the second extract 31 is composed of C5 normal hydrocarbon desorbent and most of normal alkane in the fraction of C7 and above, and the second extract 31 enters the partition rectifying tower 40; the second raffinate 32 obtained, which contains the C5 normal hydrocarbon desorbent and most of the non-normal paraffins in the C7 and above fractions, is fed to a rectifying column 60 (second raffinate rectifying column) for fourth rectifying separation, and the C5 normal hydrocarbon desorbent and the C7 and above fractions are separated from the non-normal hydrocarbons to obtain C5 normal hydrocarbon desorbent 61 (third light fraction) which is recycled to the second adsorptive separation device 30 to obtain C7 and above fractions of non-normal paraffins 62 (third heavy fraction) as reformer feedstock.

In the dividing wall rectifying column 40, the material 21 (first extract) and the material 31 (second extract) are joined as raw materials and subjected to second rectifying separation, three materials are separated, a C5 normal paraffin material 41 (first light fraction) is separated at the top of the dividing wall column, a C9 normal paraffin material 42 (first heavy fraction) and above are separated at the bottom of the dividing wall column, and a C6 to C8 normal paraffin material 43 (middle fraction) is mainly obtained from the middle of the dividing wall column. Wherein the operating conditions of the second rectification separation include: the column top operating pressure of the dividing wall column is 0.23MPa, and the reflux ratio of the column top of the dividing wall column by mass is 2.38; a portion of the feed 41 (first light fraction) is then combined with desorbent 61 (third light fraction) from rectifying column 60 as second desorbent 03 of second adsorptive separation device 30, the remainder being steam cracked feed 44; a portion 48 of the feed 42 (first heavy fraction) is combined with desorbent 52 from rectifying column 50 as first desorbent 02 of first adsorptive separation device 20, a portion of which also serves as steam cracking feed 45. Wherein the mass fraction of n-pentane in the first light fraction was 94.4 wt%, the composition of the middle fraction was shown in Table 6, the mass fraction of n-nonane in the first heavy fraction was 61.4 wt%, and the mass fraction of n-decane was 33 wt%.

Wherein the flow and composition of feed 01 (full naphtha) and of the two adsorption feeds 11 (light naphtha) and 12 (heavy naphtha) obtained by rectification are shown in table 2. The flow rate and composition of the first adsorption device 20 are shown in table 3, and the flow rate and composition of the second adsorption device 30 are shown in table 4. Wherein the mass fraction of C9 and above normal paraffins in the first desorbent 02 is 95 wt%, and the mass fraction of C5 normal paraffins in the second desorbent 03 is 94.4 wt%.

In this example, the first extract 21 and the second extract 31 were mixed as the feed for the divided wall rectifying column 40 for 51t/h in total, and the composition thereof is shown in Table 5.

The bulkhead column rectification process was simulated using Aspen plus process simulation software. The number of theoretical plates of the separation wall section is 36, the number of theoretical plates of the public rectifying section is 10, the number of theoretical plates of the public stripping section is 18, the feeding position is 16 th plates from top to bottom in the separation wall section, the separation wall is arranged on 11 th to 46 th plates of the main tower, the middle extraction position is 8 th plates from bottom to top in the separation wall section, and the feeding position are respectively positioned on two sides of the separation wall. The pressure at the top of the column is 0.23MPa and the reflux ratio is 2.38. The flow and composition of the extracted material of the dividing wall column are shown in Table 6.

The material 41 (first light fraction) extracted from the top of the partition wall is 17.0t/h, wherein, a part of the material 47 has a flow rate of 12.0t/h and is combined with the material 61 extracted from the top of the rectifying tower 60 (the flow rate is 27.9 t/h) to be used as a second desorbent 03 of the second adsorption separation device; the bottom of the partition wall is taken 42 (first heavy fraction) for 17.6t/h, and a part of the material 48 is taken at a flow rate of 11.6t/h and is combined with the bottom of the rectifying tower 50 at a flow rate of 26.7t/h to be taken as a first desorbent 02 of the first adsorption separation device.

Final material 44 (flow 5.0 t/h), material 43 (flow 16.4 t/h), material 45 (flow 6.0 t/h), and total 27.4t/h as steam cracking raw material; the top withdrawn material 51 (flow 16.4 t/h) of rectifying column 50 is used as a high-octane gasoline blending component; a bottom product 62 (flow rate: 56.4 t/h) of the rectifying column 60 was taken as a reforming raw material.

This example illustrates that the method provided by the present disclosure achieves effective separation of full range naphtha without the need for additional desorbent, reducing costs; the method can also obtain the fractions of the steam cracking raw material, the high-octane gasoline blending component and the reforming raw material, and has higher economic benefit.

Example 2

The same process as in example 1 was employed, except that:

the operating conditions of the first rectification separation are: the overhead pressure was 0.32MPa and the overhead temperature was 90 ℃.

The operating conditions of the first adsorptive separation include: the operation temperature is 155 ℃, the operation pressure is 2.5MPa, and the flow rate of liquid phase materials in the first adsorption separation device is 31.2t/h;

the operating conditions of the second adsorptive separation include: the operating temperature is 105 ℃, the operating pressure is 1.2MPa, and the flow rate of the liquid phase material in the second adsorption separation device is 68.8t/h.

This example illustrates that the fractionation of materials can be achieved by different operating conditions.

Example 3

The process flow shown in fig. 1 is adopted, and differs from that of example 1 in that:

25% by weight of the material 21 (first draw) is taken off directly as product 26, and the remaining part of the first draw is led into a dividing wall rectifying column 40; and

25% by weight of the material 31 (second draw) is taken off directly as product 36 and the remaining part of the second draw is led into a dividing wall rectification column 40. The remainder of the materials 21 and 31 was mixed together at 38.25t/h as feed to the dividing wall rectifying column 40.

The total flow rate of the material 47 in the partition wall tower top extraction 41 is 12.75t/h, and part of the material is 12.0t/h, and the material is combined with the tower top extraction 61 (the flow rate is 27.9 t/h) of the rectifying tower 60 to be used as the desorbent 03 of the second adsorption separation device; the bottom of the partition wall is taken 42 with 13.2t/h, wherein a part of the material 48 with the flow rate of 11.6t/h is combined with the bottom of the rectifying tower 50 at the bottom of 52 (with the flow rate of 26.7 t/h) to be used as the desorbent 02 of the first adsorption separation device.

The final material 26 (flow rate 5.7 t/h), 36 (flow rate 7.05 t/h), 44 (flow rate 0.75 t/h), 43 (flow rate 12.3/h), 45 (flow rate 1.6 t/h) totaling 27.4t/h are used as steam cracking raw materials; the top take-off 51 of rectifying column 50 (flow 16.4 t/h) is used as a high octane gasoline blending component; a bottom product 62 (flow rate: 56.4 t/h) of the rectifying column 60 was taken as a reforming raw material.

According to example 3, a part of the first extract liquid in the first adsorption separation device can be directly taken as the normal alkane product sending device without entering the partition rectifying tower; a part of second extract liquid in the second adsorption separation device can be directly taken as a normal alkane product sending device without entering the partition rectifying tower, so that the energy consumption of desorbent separation can be reduced.

Table 1 naphtha composition

TABLE 2 flow and composition of adsorption feed

TABLE 3 flow and composition of the first adsorption apparatus 20 in and out of materials

TABLE 4 flow and composition of the material to and from the second adsorption apparatus 30

TABLE 5 feed composition for dividing wall rectifying column

TABLE 6 flow and composition of the withdrawn material from the dividing wall rectifying column

The preferred embodiments of the present disclosure have been described in detail above with reference to the accompanying drawings, but the present disclosure is not limited to the specific details of the above embodiments, and various simple modifications may be made to the technical solutions of the present disclosure within the scope of the technical concept of the present disclosure, and all the simple modifications belong to the protection scope of the present disclosure. For example.

In addition, the specific features described in the above embodiments may be combined in any suitable manner without contradiction. The various possible combinations are not described further in this disclosure in order to avoid unnecessary repetition.

Moreover, any combination between the various embodiments of the present disclosure is possible as long as it does not depart from the spirit of the present disclosure, which should also be construed as the disclosure of the present disclosure.

Claims (10)

1. A process for the adsorptive separation of full range naphtha comprising the steps of:

s1, enabling full fraction naphtha to enter a first rectifying device for first rectifying separation to obtain light naphtha rich in C5-C6 materials and heavy naphtha rich in C8-C10 materials;

s2, enabling the light naphtha to enter a first adsorption separation device for first adsorption separation to obtain a first extract and a first raffinate; enabling the heavy naphtha to enter a second adsorption separation device for second adsorption separation to obtain a second extract and a second raffinate;

s3, enabling at least part of the first extract and at least part of the second extract to enter a partition tower for second rectification separation to obtain a first light fraction, a middle fraction and a first heavy fraction;

s4, returning at least part of the first heavy fraction to the first adsorption separation device as a first desorbent; at least a portion of the first light fraction is returned to the second adsorptive separation device as a second desorbent.

2. The method according to claim 1, wherein the total fraction naphtha has a content of normal paraffins of 20 to 50 wt.%;

the distillation range cutting point of the light naphtha and the heavy naphtha is at any value between 60 ℃ and 95 ℃; preferably, the content of C5-C6 normal paraffins in the light naphtha is 20-55 wt%, and the content of C8-C10 normal paraffins in the heavy naphtha is 15-35 wt%;

the content of the normal paraffins of C5 and below in the first light fraction is more than 90 weight percent; the content of the normal paraffins of C9 and above in the first heavy fraction is more than 90 weight percent.

3. The method according to claim 1, characterized in that the method further comprises:

at least part of the first raffinate enters a first raffinate rectifying tower to carry out third rectifying separation to obtain a second light fraction and a second heavy fraction; feeding at least part of the second raffinate into a second raffinate rectifying tower for fourth rectifying separation to obtain a third light fraction and a third heavy fraction;

returning at least a portion of said second heavy fraction to said first adsorptive separation device also as said first desorbent;

at least a portion of the third light fraction is also returned to the second adsorptive separation device as the second desorbent.

4. The method according to claim 1, wherein in step S1, the operating conditions of the first rectification separation include: the pressure at the top of the tower is 0.2-0.6 MPa, preferably 0.3-0.5 MPa, and the temperature at the top of the tower is 50-125 ℃, preferably 70-110 ℃.

5. The method according to claim 1, wherein in step S2, the first and second adsorption separation devices are liquid phase simulated moving bed adsorption separation devices;

the operating conditions of the first adsorptive separation and the second adsorptive separation each independently comprise: the operating temperature is 80-220 ℃, preferably 100-180 ℃; the operating pressure is 0.5 to 3.0MPa, preferably 0.8 to 2.5MPa.

6. The method of claim 1, wherein the adsorbents of the first and second adsorptive separation devices each independently comprise 80 to 98% by weight of an active component and 2 to 20% by weight of a binder;

optionally, the active component comprises a type a molecular sieve;

the binder is one or more selected from alumina, kaolin, bentonite and attapulgite.

7. The method according to claim 1, wherein in step S3, the number of theoretical plates of the divided wall column is 40 to 90; wherein the number of theoretical plates of the separation wall section is 25-45, the number of theoretical plates of the public rectifying section is 5-15, and the number of theoretical plates of the public stripping section is 10-30; the method further comprises the steps of:

said at least a portion of the first extract and at least a portion of the second extract are fed from the same side of the divided wall column divided wall section; the feeding position of the partition tower raw material is the 10 th to 25 th theoretical plates in the direction from top to bottom of the partition section, and the middle distillate extraction position is the 5 th to 20 th theoretical plates in the direction from bottom to top of the partition section;

optionally, the conditions of the second rectification separation include: the operation pressure of the bulkhead tower is 0.1-0.5 MPa; the reflux ratio of the top of the dividing wall tower is 1.5-4 by mass.

8. The method according to claim 1, characterized in that the method further comprises: another portion of the first light fraction and/or another portion of the first heavy fraction from the divided wall column is sent to a cracker.

9. A full range naphtha adsorptive separation system comprising: a first rectifying device, a first adsorption separation device, a second adsorption separation device, and a dividing wall column; the first rectifying device comprises a naphtha raw material inlet, a light naphtha outlet and a heavy naphtha outlet;

the first adsorption separation device comprises a light naphtha inlet, a first extract outlet, a first raffinate outlet and a first desorbent inlet; the light naphtha inlet is communicated with a light naphtha outlet of the first rectifying device;

the second adsorption separation device comprises a heavy naphtha inlet, a second extract outlet, a second raffinate outlet and a second desorbent inlet; the heavy naphtha inlet is communicated with a heavy naphtha outlet of the first rectifying device;

the partition tower is provided with a first extraction liquid inlet, a second extraction liquid inlet, a first light fraction outlet, a middle fraction outlet and a first heavy fraction outlet; the first extraction liquid inlet is communicated with a first extraction liquid outlet of the first adsorption separation device, and the second extraction liquid inlet is communicated with a second extraction liquid outlet of the second adsorption separation device; the first light fraction outlet is communicated with a second desorbent inlet of the second adsorption separation device; the first heavy fraction outlet is in communication with a first desorbent inlet of the first adsorptive separation device.

10. The system of claim 9, further comprising a first raffinate rectification column and a second raffinate rectification column;

the first raffinate rectification column comprises a first raffinate inlet, a second light fraction outlet and a second heavy fraction outlet; the first raffinate inlet is in communication with a first raffinate outlet of the first adsorptive separation device, and the second heavies outlet is in communication with a first desorbent inlet of the first adsorptive separation device;

the second raffinate rectification column comprises a second raffinate inlet, a third light fraction outlet and a third heavy fraction outlet; the second raffinate inlet is in communication with a second raffinate outlet of the second adsorptive separation device, and the third light ends outlet is in communication with a second desorbent inlet of the second adsorptive separation device.