FIELD OF THE DISCLOSURE
The present disclosure generally relates to the field of industrial equipment. Particularly, but not exclusively, the present disclosure relates to distillation columns. More particularly, the present disclosure discloses an optimized configuration for at least three product dividing wall column for improved operational flexibility and energy efficiency.
BACKGROUND OF THE DISCLOSURE
The information in this section merely provides background information related to the present disclosure and may not constitute prior art(s).
Various raw materials such as crude oil are typically mixtures of many compounds in many cases, such various raw materials are often used after being separated into compounds, instead of directly industrially used. A representative process from among chemical processes for separating a mixture is a distillation process. In general, since a distillation process separates a raw material into a high boiling component and a low boiling component when the number of components of a mixture to be separated is n, the number of distillation columns is n-1 which is obtained by subtracting 1 from the number (n). That is, a process for separating a high-purity product from a crude raw material in the conventional distillation industry mostly uses a structure in which 2 distillation columns are continuously arranged.
In refineries and chemical industries, distillation is widely employed for separating two or more products in a fluidic mixture and is an energy-intensive process. Fig. 1 illustrates a conventional configuration having two column systems for separating three products from a mixture. In the first column, a first cut is collected as the top product, and a mixture of the remaining two products is collected at the bottom. Subsequently, the other two cuts are separated in the next column. In this system,

two condensers CI, C2, and two reboilers Rl, R2 for each column Bl, B2 along with other equipment are needed. One major disadvantage of this configuration is that it requires more equipment and a bigger land area for installation. Another disadvantage is that the energy consumption of multiple types of equipment is also high.
Another configuration is illustrated in Fig. 2, whereby the two columns are replaced by a single column with a dividing wall. In such a configuration, three products can be separated in a single column. The dividing wall is placed in the center and light components are prefractionation side (feed side of the column) and removed as a top product. The middle product is removed from the other side of the dividing wall and the third product is separated from the bottom. In such a configuration, the dividing wall column is B3 with condenser C3 and reboiler R3 for three products column and column B4 with a dividing wall along with condenser C4 and reboiler R4 for four products' column. Although this configuration is more feasible than Fig. 1, it has many limitations associated with it. One major limitation is the non-flexibility of the distributing liquid and vapor. Generally, the distribution of liquid and vapor is attained by designing column internals such that liquid and vapor are distributed as per design ratio. Hence, liquid and vapor distribution are fixed for certain configurations and cannot be changed with the change of feed or product specifications. In addition, sometimes the liquid is distributed by taking out the liquid and distributed and then pumped back. This method requires extra equipment and extra pumping cost for the distribution.
Accordingly, there is a need in the art to provide an improved configuration of dividing wall columns with less equipment and a better method of liquid distribution to enhance the operability and purity of products. The present disclosure is directed to overcome the one or more limitations stated above or any other limitations associated with the prior art.

SUMMARY OF THE DISCLOSURE
The present disclosure overcomes one or more drawbacks of conventional arrangements as described in the prior art and provides additional advantages through an arrangement as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
In one non-limiting embodiment of the present disclosure, a dividing wall column for separating a multi-component fluid comprising the main column, a dividing wall positioned inside the main column which is configured to divide the main column into a first side and a second side, one or more feed inlet conduit configured to supply a feedstock of the multi-component fluid to the main column. In this optimized configuration for operational flexibility, a portion of the feedstock is introduced to the first side of the main column and a remaining portion of the feedstock is introduced to the second side of the main column.
In an embodiment of the present disclosure, the first side is a prefractionation side, and the second side is a product side.
In an embodiment of the present disclosure, an optimized feed distribution ratio for the portion of the feedstock introduced in the first side and the second side is adjusted to meet a product specification.
In an embodiment of the present disclosure, an optimized value of 9 wt. % feed split is introduced to the second side of the dividing wall.
In an embodiment of the present disclosure, the dividing wall column comprises an overhead condenser configured to receive an overhead vapor stream from the main column.

In an embodiment of the present disclosure, the dividing wall column comprises a reboiler configured to receive at least a portion of a bottom liquid stream for vaporization and returning that portion to the main column.
In an embodiment of the present disclosure, a portion of reflux is collected as a first product and the remaining amount is sent back to the main column as reflux and is distributed across the divided wall.
In an embodiment of the present disclosure, the products are taken out from the second side of the main column.
In an embodiment of the present disclosure, a stream configured to be cooled passes through the overhead condenser and a stream configured to be heated passes through the reboiler.
In an embodiment of the present disclosure, a process for separating a multi-component fluid using a dividing wall column is disclosed. The process comprising introducing a major portion of a feedstock into the first side of the main column and introducing a remaining portion of the feedstock into a second side of the main column. After that, heating the multi-component fluid to provide a first product, a second product, a third product, and a fourth product. Further, condensing a vapor from the main column with an overhead condenser and heating a liquid from the main column with a reboiler. Lastly, collecting the first product from a top region of the main column, collecting the second product from the second side of the main column, collecting the third product from a lower side of the main column, and collecting the fourth product from the bottom of the column. The process as disclosed is optimized by adjusting a feed distribution ratio to meet the product specification for improved operational flexibility.

The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF FIGURES
The novel features and characteristics of the disclosure are set forth in the description. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following description of an illustrative embodiment when read in conjunction with the accompanying drawings. One or more embodiments are now described, by way of example only, with reference to the accompanying drawings wherein like reference numerals represent like elements and in which:
FIG. 1 illustrates an existing configuration of a conventional two column system, in accordance with the prior art.
FIG. 2 illustrates an existing configuration of a three cut and more than three cut column with a dividing wall, in accordance with the prior art.
FIG. 3 illustrates a schematic representation of the optimized configuration for improved operational flexibility and energy efficiency in a dividing wall column, according to an embodiment of the present disclosure.
Skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.

DETAILED DESCRIPTION
While the disclosure is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described in detail below. It should be understood, however that it is not intended to limit the disclosure to the particular forms disclosed, but on the contrary, the disclosure is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the disclosure as defined by the appended claims.
Before describing in detail embodiments, it may be observed that the novelty and inventive step that are in accordance with the present disclosure resides in an optimized configuration for improved operational flexibility and energy efficiency in a dividing wall column. It is to be noted that a person skilled in art can be motivated from the present disclosure and modify the various constructions of the proposed invention. However, such modification should be construed within the scope and spirit of the disclosure. Accordingly, the drawings are showing only those specific details that are pertinent to understanding the embodiments of the present disclosure so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein.
The terms "comprises", "comprising", or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, device that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by "comprises... a" does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.
As used herein, the term "feedstock" can be a feed from which three or more than three products are separated, which include various hydrocarbon molecules, such

as straight-chain, branched, or cyclic alkanes, alkenes, and alkynes, and optionally other substances, such as gases, e.g., hydrogen, or impurities, such as heavy metals, and sulfur and nitrogen compounds. The stream can also include aromatic and non-aromatic hydrocarbons. Moreover, the hydrocarbon molecules may be abbreviated
CI, C2, C3 Cn where "n" represents the number of carbon atoms in one or more
hydrocarbon molecules.
As used herein, the term "dividing wall column" generally means a column including a substantially fluid-tight vertical wall extending through a significant portion of the column's height and located in a central portion of the column. Thus, a central portion of the column can be divided into at least two vertical, parallel vapor-liquid contacting sections. The top and bottom of the wall terminate in the column at a point distant from the respective end of the column such that there is open communication across the column interior at the top and bottom of the dividing wall.
Reference will now be made to the exemplary embodiments of the disclosure, as illustrated in the accompanying drawings. Wherever possible same numerals will be used to refer to the same or like parts.
According to an embodiment of the present disclosure, as shown in Fig. 3, there is provided an optimized configuration of a dividing wall column for improved operational flexibility and energy efficiency. In a non-limiting embodiment, the proposed configuration of the dividing wall column may be employed where three or more than three products are to be separated in a single column. As shown, the proposed configuration comprises a main column (B5) having a generally vertical configuration. A feed inlet conduit is disposed of in a middle region to direct a feedstock mixture to the main column (B5). An overhead condenser (C5) is connected to an overhead stream of the main column (B5). The overhead condenser (C5) is configured to receive an overhead stream from the main column (B5). In an embodiment, the overhead condenser (C5) is a total condenser. A reboiler (R5) is

configured in the bottom section of the main column (B5). The reboiler (R5) is configured to receive at least a portion of a bottom stream and returning that portion to the main column (B5). In an embodiment, the heating medium of the reboiler (R5) comprises column bottoms. The main column (B5) comprises a dividing wall (5) disposed of vertically in a central region of the main column (B5).
In an aspect, the dividing wall (5) divides a middle section of the main column (C5) into a first side (6) and a second side (7). In a preferred embodiment, the dividing wall (5) is a dividing imperforate wall. Typically, a significant portion of a column height is taken by the dividing wall. The embodiments as described herein can utilize a dividing wall column either in combination with a non-divided column or alone to produce at least three or four products. The first side (6) is a prefractionation side, and the second side (7) is a product side. The feedstock mixture comprising one or more products to be separated is supplied through one or more feed inlet conduits.
In an exemplary embodiment, the feedstock comprises a first product (1), a second product (2), a third product (3), and a fourth product (4). During operation, the first product (1) is collected from the top side of the main column (B5), the second product (2) is collected from the second side (7) of the main column (B5). In an embodiment, the second side (7) is opposite to the first side (6) of the main column (B5) where the inlet is provided. The third product (3) is collected from a lower side of the main column (C5) and the fourth product (4) is collected from the bottom of the main column (C5). In a preferred embodiment, each section often contains fractionation trays and/or packing intended to promote separation. During operation, the feed is distributed in two parts and one part is sent to the first side (6) of the dividing wall of the main column (C5) and the remaining part is sent to the second side (7) of the dividing wall (5). The optimized feed distribution ratio for the portion of the feedstock introduced in the first side (6) and the second side (7) is adjusted to meet a product specification.

In an aspect, the duty for the overhead condenser (C5) can be provided by a cooling stream using any suitable fluid, such as water. The duty for the reboiler (R5) can be provided by heating streams such as steam or hot oil. In a preferred embodiment, a portion of reflux is collected as a first product (1) and the remaining amount is sent back to the main column (B5) as reflux. In an exemplary embodiment, the reflux of the main column is distributed into two parts and send to two different locations of the main column.
A process for separating a multi-component fluid using the dividing wall column is now disclosed. Generally, the dividing wall column can receive a feedstock that may include a plurality of naphtha components. The major portion of the feedstock is fed into the first side (6) of the main column (B5) and the remaining portion of the feedstock is fed into the second side (7) of the main column (B5). The feedstock can provide an overhead stream including light naphtha (i.e. first product), a side stream including middle naphtha (i.e. second product), and a bottom stream that can include an aromatic (i.e. third product) and heavy naphtha (i.e. fourth product). Generally, as the feedstock enters the main column (B5), the lighter material can pass as the overhead stream passing through the overhead condenser (C5) and then to the reflux drum (D5). A part can be returned as reflux and another part may be withdrawn as a light naphtha product from the reflux drum (D5). The heavier material in the main column (B5) can pass out as a bottom stream with a portion taken as a heavy naphtha product and another part as a return to the main column which passes through the reboiler (R5) before entering the main column (B5). Generally, any suitable heating stream, as described above, can be used to heat the reboiler (R5).
Example
The disclosed example is related to the application of the dividing wall column technology in the naphtha splitter unit in accordance with the present disclosure. In a typical naphtha splitter unit, typical feed naphtha as per Table-1 is split into four

cuts. In the present application conventional two-column naphtha splitter unit is converted into the dividing wall column. The present example shows the operational flexibility of the dividing wall column with the change of feed is maintained by splitting feedstock into two sections across the dividing wall in accordance with the present disclosure.
The illustrative example considers two design feed cases as mentioned in Table 1. The naphtha splitter column with the dividing wall is designed for design case 2. The naphtha splitter column with the dividing wall is configured to withdraw four products. Liquid and vapor split is fixed according to design case 2 to meet the product specifications. Now when the design case 1 feed is introduced in the main column, the product specifications are not met due to a change in feed. The liquid distribution across the dividing wall is fixed as hardware is designed for design case 2 feed. Therefore, the present disclosure proposes that to meet the design specifications, a part of the feed is introduced in the second side of the dividing wall to change the liquid distribution across the wall.
Table 1: Feed Specification

Parameters Design Case 1 Design Case 2
Benzene in feed, vol% 0.3 1.8
Naphtha, ASTM 15°CTBPcut- 170 °C TBP cut 15°C TBP cut -170 °C TBP cut
Table 1 shows a feed specification in which feed is typical Naphtha of boiling range up to 170 °C TBP. The feed comprises Paraffins, Olefins, Naphthenes, and Aromatics. The feed further comprises a Benzene in the range of 0.3 - 1.8 vol%. The objective of the process is to separate four products of product specifications as per table 2.

Table 2: Product Specifications

Parameters
Cutl (C5-C6 Cut) Benzene recovery 40%
Cut2 (C6-C7P cut) C7 Naphthene component recovery <20 vol%
Cut3 (C7N-110 cut) C7 Naphthene component recovery < 30 vol%
Cut4 (110-150 Cut) ASTM D86 5% recovery >110°C
Table 2 illustrates a product specification in which the first product is C5-C6 cut where Benzene content in the product stream is limited to 40 vol%. The second product consists of C6-C7 Paraffins, in which C7 Naphthene in the stream is limited to 20 vol%. The third product is C7 Naphthenes to 110 cut, C7 Naphthenes in the product stream is limited to 30 vol%. The fourth product is drawn from the bottom which contains the remaining heavy part of the feed. The ASTM D86 temperature of 5% recovery of this product is maintained to 110 °C.
Table 3: Design Specifications of two cases

Parameters Design Case 1 Design Case 2
Feed to column Total feed to prefractionation side of the column Total feed to prefractionation side of the column
Reboiler Duty, MMKcal/hr 12.8 13
Vapour Split, % 43-44 45-49
Liquid Split, % 9-12 13-22
Reflux Ratio 4.0 3.2
Table 3 shows design specifications for two design feed cases. If the divided wall is designed as per design case 1, reboiler duty and reflux requirement would be 12.8 MMKcal/hr and 4.0 respectively. A liquid split across the divided wall to be

maintained 9-12% accordingly vapour split would be 43-44 %. Similarly, for design case 2 design specifications are reported in Table 3. The column is designed according to controlling case design case 2. When design case 1 is introduced in the column to meet the product specification becomes difficult with the liquid split of design case 2. To meet the product specifications feed is distributed across the divided wall in an optimized manner.
The two sets of runs are conducted with 5 wt% and 9 wt% feed split to the second section. The product specifications are met with a 5 wt% feed split in the existing naphtha splitter column. When feed split to other section is increased to 9 wt%, reboiler duty is decreased further. It is further observed that if the feed ratio is increased beyond 9 wt% i.e., at 10 wt% or more, the reboiler duty will start increasing. Therefore, it can be stated that the 9 wt% feed split is an optimized value after analyzing of results for different feed split ratios.
Therefore, it can be summarized that in the above two cases governing case is design case 2, hence the dividing wall column is designed as per specifications of design case 2. Thus, liquid distribution is fixed according to requirements of design case 2 for meeting the product specifications and column internals are designed for this liquid distribution. However, when the design case 1 feed is introduced in the column, to meet the product specifications it requires a different liquid split according to design case 1 specification. As liquid split is fixed and cannot be changed, therefore, to maintain operational flexibility, to change the liquid across the wall part of the feed is sent to the other side of the dividing wall.

Table 4: Case study analysis

Parameters Design case 1 as feed Design case 1 with 5 wt% feed to the second side of dividing wall Design case 1 with 9 wt% feed to the second side of dividing wall Design case 1 with 10wt%feed to the second side of dividing wall
Feed to column Total feed to prefractionation side of the column 5 wt% of feed is sent to the second side of the dividing wall column 9 wt% of feed is sent to the second side of the dividing wall column 10 wt% of feed is sent to the second side of the dividing wall column
Reboiler
Duty,
MMKcal/hr 12.6 12.48 12.37 12.45
Vapour Split, % 45-49 45-49 45-49 45-49
Liquid Split, % 13-22 13-22 13-22 13-22
Reflux Ratio 4.16 4.11 4.06 4.1
The above analysis showed that the column was designed for design case 2 and vapour and liquid distribution were fixed as per design case 2. When design case 1 feed is introduced to the column, product specifications are met by shifting part of the feed to other section of the dividing wall column.
Accordingly, the proposed configuration addresses the limitation of low installation space. In addition, the configuration ensures liquid and vapor distribution in a dividing wall column with improved flexibility of operation. Further, the proposed configuration is robust, economical, and has a simple construction.

The disclosure has been described herein, with reference to certain embodiments, in order to enable the reader to practice the disclosure without undue experimentation. However, a person having ordinary skill in the art will readily recognize that many of the components and parameters may be varied or modified to a certain extent or substituted for known equivalents without departing from the scope of the disclosure. It should be appreciated that such modifications and equivalents are herein incorporated as if individually set forth. In addition, titles, headings, or the like are provided to enhance the reader's comprehension of this document and should not be read as limiting the scope of the present disclosure. Therefore, it is intended that the present disclosure covers such modifications and variations provided they come within the ambit of the appended claims and their equivalents.
Equivalents:
With respect to the use of substantially any plural and/or singular terms herein,
those having skill in the art can translate from the plural to the singular and/or from
the singular to the plural as is appropriate to the context and/or application. The
various singular/plural permutations may be expressly set forth herein for sake of
clarity.
It will be understood by those within the art that, in general, terms used herein, and especially in the appended claims (e.g., bodies of the appended claims) are generally intended as "open" terms (e.g., the term "including" should be interpreted as "including but not limited to," the term "having" should be interpreted as "having at least," the term "includes" should be interpreted as "includes but is not limited to," etc.). It will be further understood by those within the art that if a specific number of an introduced claim recitation is intended, such an intent will be explicitly recited in the claim, and in the absence of such recitation, no such intent is present. For example, as an aid to understanding, the following appended claims may contain usage of the introductory phrases "at least one" and "one or more" to introduce claim recitations. However, the use of such phrases should not be

construed to imply that the introduction of a claim recitation by the indefinite articles "a" or "an" limits any particular claim containing such introduced claim recitation to inventions containing only one such recitation, even when the same claim includes the introductory phrases "one or more" or "at least one" and indefinite articles such as "a" or "an" (e.g., "a" and/or "an" should typically be interpreted to mean "at least one" or "one or more"); the same holds true for the use of definite articles used to introduce claim recitations. In addition, even if a specific number of an introduced claim recitation is explicitly recited, those skilled in the art will recognize that such recitation should typically be interpreted to mean at least the recited number (e.g., the bare recitation of "two recitations," without other modifiers, typically means at least two recitations or two or more recitations). Furthermore, in those instances where a convention analogous to "at least one of A, B, and C, etc." is used, in general such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, and C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). In those instances, where a convention analogous to "at least one of A, B, or C, etc." is used, in general, such a construction is intended in the sense one having skill in the art would understand the convention (e.g., "a system having at least one of A, B, or C" would include but not be limited to systems that have A alone, B alone, C alone, A and B together, A and C together, B and C together, and/or A, B, and C together, etc.). It will be further understood by those within the art that virtually any disjunctive word and/or phrase presenting two or more alternative terms, whether in the description, claims, or drawings, should be understood to contemplate the possibilities of including one of the terms, either of the terms or both terms. For example, the phrase "A or B" will be understood to include the possibilities of "A" or "B" or "A and B." While various aspects and embodiments have been disclosed herein, other aspects and embodiments will be apparent to those skilled in the art. The various aspects and embodiments disclosed herein are for purposes of illustration and are not intended to be limiting, with the true scope and spirit being indicated by the following claims.

Reference numerals:

Reference Number Description
Prior art
A, B, C, D Multi-component feed
B1,B2, B3,B4 Column
CI, C2, C3, C4 Overhead condenser
Rl, R2, R3, R4 Reboiler
A Low boiling product
B Medium boiling product
C Medium/High boiling product
D High boiling product
Present Invention
B5 Main column
C5 Overhead condenser
R5 Reboiler
D5 Reflux drum
1 First product
2 Second product
3 Third product
4 Fourth product
5 Dividing wall
6 First side
7 Second side

We claim:
1. A dividing wall column for separating a multi-component fluid comprising:
a main column (B5);
a dividing wall (5) positioned inside the main column (B5) which is configured to divide the main column (B5) into a first side (6) and a second side (7);
one or more feed inlet conduit configured to supply a feedstock of the multi-component fluid to the main column;
wherein, for operational flexibility, a portion of the feedstock is introduced to the first side (6) of the main column (B5) and a remaining portion of the feedstock is introduced to the second side (7) of the main column (B5).
2. The dividing wall column as claimed in claim 1, wherein the first side (6) is a prefractionation side, and the second side (7) is a product side.
3. The dividing wall column as claimed in claim 1, wherein an optimized feed distribution ratio for the major portion of the feedstock is introduced in the first side (6) and the second side (7) is adjusted to meet a product specification.
4. The dividing wall column as claimed in claim 3, wherein an optimized value of 9 wt. % feed split is introduced to the second side (7) of the dividing wall column.
5. The dividing wall column as claimed in claim 1, comprises an overhead condenser (C5) configured to receive an overhead vapor stream from the main column (B5).

6. The dividing wall column as claimed in claim 1, comprises a reboiler (R5) configured to receive at least a portion of a bottom liquid stream for vaporization and returning that portion to the main column (B5).
7. The dividing wall column as claimed in claim 1, wherein a portion of reflux is collected as a first product (1) and the remaining amount is sent back to the main column (B5) as a reflux and is distributed across the divided wall
(5).
8. The dividing wall column as claimed in claim 1, wherein the products are taken out from the second side (7) of the main column (B5).
9. The dividing wall column as claimed in claim 4 and claim 5, wherein a stream configured to be cooled passes through the overhead condenser (C5) and a stream configured to be heated passes through the reboiler (R5).
10. A process for separating a multi-component fluid using a dividing wall column, the process comprising:
introducing a major portion of a feedstock into a first side (6) of a main column (B5) and introducing a remaining portion of the feedstock into a second side (7) of the main column (B5);
heating the multi-component fluid to provide a first product (1), a second product (2), a third product (3), and a fourth product (4);
condensing a vapor from the main column (B5) with an overhead condenser (C5) and heating a liquid from the main column (B5) with a reboiler (R5);
collecting the first product (1) from a top region of the main column (B5), collecting the second product (2) from the second side (7) of the main column (B5), collecting the third product (3) from a lower side of the main column (B5), and collecting the fourth product (4) from the bottom of the main column (B5);

wherein the process is optimized by adjusting a feed distribution ratio to meet the product specification for improved operational flexibility.