System and method for producing polymer-grade propylene from unsaturated LPG using a single tower

Abstract

A separation process and system for separating high-purity polymer-grade propylene products from a mixed liquefied petroleum gas stream. In the embodiment, the system and method combine the functions of a de-ethane unit and a de-propane unit with a C3 splitter system to separate high-purity polymer-grade propylene products from a liquefied petroleum gas stream, thereby eliminating the need for separate de-ethane units, de-propane units, and a C3 splitter.

Description

Detailed Description of the Invention

[0001] This application claims the benefit of Indian Patent Application No. IN202311045057, filed on July 5, 2023. This document is hereby incorporated by reference in its entirety for all purposes as if fully set forth herein. [Technical Field]

[0002] The present disclosure relates to separation processes and systems. In particular, the system and method can separate high purity polymer grade propylene product from a mixed liquefied petroleum gas stream. In an embodiment, the described system and method combine the functions of a deethanizer column and a depropanizer column with a C3 splitter system. [Background Art]

[0003] Polymer grade propylene (PGP) is a high purity form of propylene mainly used as a raw material in the production of polypropylene, one of the most widely used plastics. Polypropylene has various applications due to its versatility, durability, and resistance to chemicals and heat. PGP has strict specifications, and its purity requirements in the industry vary from 99.5% (vol) to 99.8% (vol). [[ID=IS]]

[0004] PGP is typically recovered from liquefied petroleum gas (LPG). This process usually requires multiple sequentially arranged distillation columns to achieve optimal recovery at a high purity level of propylene from the treated unsaturated gas. Known systems use two or three distillation columns. A two-column system typically includes a depropanizer column followed by a C3 splitter column. A three-column system typically includes a depropanizer column followed by a deethanizer column followed by a C3 splitter column.

[0005] Figure 1 shows a conventional multi-stack system 100. In the illustrated example, the scheme includes three distillation columns. As illustrated, the processed LPG stream 102 is fed into the multi-stack system. The multi-stack system includes a depropane column 110, a deethane column 120 downstream of the depropane column 110, and a C3 splitter column 130 downstream of the deethane column 120. As illustrated, each column may include its respective condenser and reboiler systems 116, 118, 126, 128, 136, and 138. The depropane column 110 is typically configured to remove propane and light hydrocarbons from the processed LPG stream. As illustrated, the product stream of C4 (butane and butene) and, if present, higher hydrocarbons (collectively referred to as "C4+") may be removed as the bottom product stream 114 of the depropane column 110. Next, the overhead stream 112 of the depropane planter tower 110 is normally supplied to the deethane planter tower 120, where the light fraction C2 (ethane and ethylene) is removed via the overhead stream 122, and some of it is sent to the exhaust gas system. The C3-rich stream from the bottom product stream 124 of the deethane planter tower 120 is instead supplied to the C3 splitter tower 130, which is configured to separate PGP products from propane products. As illustrated, the overhead stream 132 of the C3 splitter tower 130 discharges the remaining light fractions and sends them to the exhaust gas system. A side draw 140 is used to provide the PGP product stream, while the bottom product stream 134 of the C3 splitter tower 130 provides the propane product stream.

[0006] While effective, multi-tower systems require significant capital investment and large site space due to the multiple towers and other auxiliary equipment. Furthermore, multi-tower systems tend to be energy-inefficient due to remixing effects.

[0007] Therefore, there is a need for improved systems that offer advantages over currently used processes and equipment. [Overview of the prefecture]

[0008] Examples of systems and methods for producing PGP from unsaturated LPG using a single tower can significantly avoid one or more of the problems arising from the limitations and shortcomings of the prior art, or at least provide a useful alternative to the public.

[0009] The examples described herein can provide systems and methods that are more energy-efficient than those currently available.

[0010] The embodiments described herein can achieve a reduction in capital investment compared to currently available options.

[0011] The embodiments described herein require less site space compared to those currently available.

[0012] Additional features and advantages of the examples described herein are described below, some of which may be apparent from the description or acquired through the implementation of this disclosure. The purposes and other advantages of this disclosure are realized and achieved by the specification and claims described herein, as well as the structures specifically indicated in the accompanying drawings.

[0013] In the examples, this specification describes a process for recovering polymer-grade propylene from liquefied petroleum gas (LPG). This process may include supplying an LPG stream to a pre-distillation section of a split-wall column, and generating a polymer-grade propylene product stream and a propane product stream by the split-wall column, the polymer-grade propylene product stream may be obtained as an overhead stream or a side-draw stream.

[0014] In the embodiment, the process may include generating a light fraction stream and a C4+-containing stream.

[0015] In the examples, the light fraction stream may be generated as an overhead stream, the polymer-grade propylene product stream may be generated as a first side-draw stream, the propane product stream may be generated as a second side-draw stream, and the C4+-containing stream may be generated as a bottom product stream.

[0016] In the embodiment, the first side draw stream may be drawn from below the overhead stream, and the second side draw stream may be drawn from below the first side draw stream.

[0017] In the embodiment, the second side drawstream may be drawn from the main fractional distillation section of the split wall tower.

[0018] In the examples, the light fraction stream may be generated as the first overhead stream, the polymer-grade propylene product stream may be generated as the second overhead stream, the propane product stream may be generated as the side draw stream, and

[0019] The C4+-containing stream can be generated as the bottom product stream.

[0020] In the embodiment, the drawstream may be drawn from the main fractional distillation section of a split wall tower.

[0021] In the embodiment, the process may include passing at least a portion of the bottom product stream through a reboiler and extracting the remainder.

[0022] In the embodiment, the process may include sending a polymer-grade propylene product stream to a first storage unit and a propane product stream to a second storage unit.

[0023] In an embodiment, this specification describes a dividing wall column for producing polymer-grade propylene from liquefied petroleum gas (LPG). This dividing wall column may include one or more dividing walls within the dividing wall column, the dividing walls being configured to define a pre-fractionation section and a main fractionation section within the dividing wall column, an LPG feed configured to input an LPG feed into the pre-fractionation section, one or more overhead streams, one or more side draw streams that may include a propane product side draw stream withdrawn from the main fractionation section of the dividing wall column, a bottom product stream, and a reboiler system configured to heat at least a portion of the bottom product stream and recycle it to the dividing wall column.

[0024] In an embodiment, the one or more dividing walls may include two dividing walls disposed at different heights within the dividing wall column.

[0025] In an embodiment, at least one of the one or more dividing walls may extend downward from the upper end of the dividing wall column.

[0026] In an embodiment, one dividing wall may at least partially overlap another dividing wall.

[0027] In an embodiment, the one or more overhead streams may include an overhead stream of a light fraction.

[0028] In an embodiment, the one or more side draw streams may include a polymer product stream of a propylene grade withdrawn from below the one or more overhead streams.

[0029] In an embodiment, the one or more overhead streams may include a first overhead stream and a second overhead stream, and one of the first overhead stream or the second overhead stream may include a polymer product stream of a propylene grade.

[0030] In an embodiment, the dividing wall column may include a condenser system for each of one or more overhead streams.

[0031] In an embodiment, the dividing wall column may include an overhead recirculation line for each of one or more overhead streams, and each overhead recirculation line is configured to recirculate at least a portion of the respective overhead stream.

[0032] In an embodiment, a scheme for producing polymer-grade propylene from liquefied petroleum gas (LPG) is described herein. This scheme may include a single distillation column, the single distillation column being a dividing wall column, the dividing wall column including one or more dividing walls within the dividing wall column configured to define a prefractionation section and a main fractionation section within the dividing wall column, an LPG feed configured to introduce an LPG feed in the prefractionation section, one or more overhead streams, one or more side draw streams that may include a propane product side draw stream withdrawn from the main fractionation section of the dividing wall column, and a bottom product stream.

[0033] Any combination of the features listed above may be implemented without departing from the spirit or scope of the present disclosure. It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the claimed disclosure.

[0034] The accompanying drawings are included to provide a further understanding of the present disclosure, are incorporated herein, and constitute a part hereof, and show embodiments of the present disclosure and together with the description serve to explain the principles of the present disclosure.

Brief Description of the Drawings

[0035] [Figure 1]This figure shows a conventional system currently available in the technical field for fractional distillation of LPG fluid to produce PGP using a de-ethane unit, a de-propane unit, and a C3 splitter. [Figure 2] This figure shows an example of an exemplary system and method for fractional distillation of LPG fluid according to the present disclosure. [Figure 3] This figure shows an example of an exemplary system and method for fractional distillation of LPG fluid according to the present disclosure. [Modes for carrying out the invention]

[0036] Examples disclose processes and systems for recovering PGP from LPG. In examples, the processes and systems may include schemes having a single tower capable of achieving the same PGP recovery, quality, and high purity as achieved by operating multiple towers sequentially. As previously stated, high purity of PGP refers to a purity of at least 99%(vol), e.g., about 99.5%(vol) to about 99.8%(vol). In examples, the single tower may include a segmented-wall tower.

[0037] In examples, the single-column scheme described herein may offer significant advantages compared to conventional multiple sequentially arranged distillation columns for producing high-purity propylene from LPG. Where used herein, the term “single” referring to the column in the scheme described herein is intended to mean that the scheme does not include any other distillation columns used to distill PGP from the LPG feed stream. In examples, the single-column scheme described herein may require less energy and capital investment, and / or site space, compared to conventional schemes. In examples, this scheme can separate PGP from all other components using a single column, whereas conventional schemes may use three columns sequentially to achieve the same level of separation. Thus, the subject invention helps to save site space. In examples, the described scheme may use only one condenser and reboiler, compared to conventional schemes where each column in a multi-column system typically includes its own condensation and reboiler systems. Thus, this described scheme may be less capital-intensive. In examples, the total number of trays in the scheme described herein may be less than the cumulative number of trays required in a conventional three-column system. Therefore, the schemes described herein may be less capital-intensive than multi-tower systems. In addition, for example, the schemes described herein may require lower reboiling and condensation loads than conventional three-tower systems, which means lower utility consumption and therefore lower operating costs.

[0038] In the examples, a single column may include a fractional distillation column. As used herein, the term “fractional distillation column” may refer to any system, device, or combination of systems and / or devices suitable for the selective separation of a mixture containing two or more components with different boiling points. In the examples, fractional distillation columns may include distillation columns, rectifier columns, stripping columns, splitter columns, and the like.

[0039] In the embodiment, a single tower may include a segmented-wall tower (i.e., a tower containing one or more segmented walls). In the embodiment, a single tower may include a fractional-distillation tower having one or more segmented walls inside. For the purposes of this description, a segmented-wall tower means a tower containing “segmented walls,” where “segmented walls” means any partition plate provided within the internal space of the tower to provide different sections within the tower. In the embodiment, a segmented wall in a segmented-wall tower may separate the internal space of the segmented-wall tower, providing a first fractional-distillation section or pre-fractional-distillation section on one side of the wall and a second fractional-distillation section or main fractional-distillation section on the other side of the wall. The segmented wall may be segmented or continuous. The segmented wall may be parallel or non-parallel to the longitudinal axis of the tower. The first fractional-distillation section and the second fractional-distillation section may have the same or different cross-sectional area, volume, or both. In one or more specific embodiments, the tower may have a circular cross-section, and a dividing wall may bisect the cross-section of the tower to provide equal cross-sectional areas within a first fractionation section and a second fractionation section. In embodiments, a stripping zone may be located at least below the pre-fractionation section.

[0040] In the embodiment, a single tower may include one partition plate or dividing wall. In the embodiment, a single tower may include more than one partition plate or dividing wall (for example, two partition plates or dividing walls). In the embodiment, a partition plate or dividing wall may be located at the bottom of a single tower, in the middle of a single tower, or at the top of a single tower. In the embodiment, a partition plate or dividing wall may extend across more than one portion of a single tower. In the embodiment, if a single tower includes more than one partition plate or dividing wall, the partition plate or dividing wall may be located at different heights within the single tower.

[0041] In the embodiment, the processed LPG stream can be received in the pre-distillation section of a split-wall column, where various hydrocarbon components are separated by distillation. Partition plates within the split-wall column may be configured to restrict the mixing of fluids on either side of the plate, which may contain different compositions. In the embodiment, this can make the distillation process more energy-efficient.

[0042] In the embodiment, the split-wall column may be configured to separate the treated unsaturated LPG into multiple streams. In the embodiment, the split-wall column may be configured to heat the LPG and separate it into four streams: a light fraction stream, a PGP product stream, a propane product stream, and a C4+ product stream.

[0043] In the examples, the light fraction stream may contain lighter compounds (e.g., ethane and ethylene). In the examples, the light fraction stream may be removed from the top of the column. In the examples, removing the light fraction stream may help to meet the light fraction specifications of the PGP.

[0044] In the embodiment, PGP may be extracted via a first side draw located several trays below the top tray of the column. In the embodiment, trays between the overhead stream and the PGP draw can help ensure the necessary separation of the light fraction from the PGP product. In the embodiment, the first side draw product stream may be recovered as the main product and sent to a first storage unit.

[0045] In the example, propane can be concentrated in the main fractional distillation section of a split-wall column. In the example, a second side draw is taken from a suitable position below the first side draw, resulting in a propane product stream. In the example, the second side draw product stream may be sent to a second storage unit.

[0046] In the embodiment, the C4+ component may be extracted as a bottom product stream from the bottom of the main fractional distillation section of the split-wall column. In the embodiment, at least a portion of the bottom product stream of the main fractional distillation of the split-wall column may be passed through a reboiler and recirculated back into the split-wall column. In this way, it may be possible to transfer heat to the bottom of the split-wall column. In the embodiment, the remaining portion of the bottom product stream that is not passed through the reboiler may be extracted as the bottom product.

[0047] In this way, the processes and systems described herein can integrate the functions of a propane removal tower, an ethane removal tower, and a C3 splitter tower, which are typically found in multi-tower schemes, into a single split-wall tower. This single-tower scheme can achieve higher energy efficiency than conventional multi-tower schemes.

[0048] Next, we will refer in detail to one or more examples shown in the attached drawings.

[0049] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those generally understood by those skilled in the art to which this disclosure belongs. All patents, patent applications, published applications and publications, websites and other public materials referenced throughout this disclosure are incorporated by reference throughout unless otherwise noted. If a term has multiple definitions in this disclosure, the definition in this section shall prevail. Where a URL or other such identifier or address is referenced, it is understood that such identifiers may change and information on the Internet may change, although equivalent information may be found by searching the Internet. This reference demonstrates that such information is available and publicly distributed.

[0050] As used herein, the singular forms "a," "an," and "the" refer to multiple objects unless the context clearly indicates otherwise.

[0051] The terms "first," "second," "third," etc., as used herein, can describe various elements, components, regions, layers, and / or sections, but these elements, components, regions, layers, and / or sections should not be limited by these terms. These terms may only be used to distinguish one element, component, region, layer, or section from another region, layer, or section. The terms "first," "second," etc., and other numerical terms, as used herein, do not imply order or sequence unless clearly indicated by the context. Thus, the first element, component, region, layer, or section described below may be referred to as the second element, component, region, layer, or section without departing from the teaching of the exemplary embodiments.

[0052] As used herein, ranges and quantities may be expressed as “approximately” a specific value or range. “Approximately” also includes exact quantities. Therefore, “approximately 5 percent” means approximately 5 percent in addition to 5 percent. The term “approximately” means within the range of typical experimental error for the intended use or purpose.

[0053] As used herein, "and / or" includes all possible combinations of one or more of the related list items.

[0054] As used herein, “combination” refers to any association between two or more items. This association may be spatial, or it may refer to the use of two or more items for a common purpose.

[0055] As used herein, “comprising” and “comprises” are intended to be open-ended, meaning “including but not limited to” and “includes but not limited to,” respectively, and therefore include not only the elements described but also any additional elements.

[0056] As used herein, “optional” or “optional” means that the event or situation described thereafter may or may not occur, and the description includes both the possibility and the possibility of the event or situation occurring. For example, an optional component in the system means that the component may or may not be present in the system.

[0057] As used herein, “substantially” means “most of but not all of what is identified.”

[0058] Figures 2 and 3 show examples of single-tower schemes described herein. In embodiments, the illustrated embodiments may integrate the functions of a de-ethane unit, a de-propane unit, and a C3 splitter into a single split-wall tower for PGP production. In embodiments, the single split-wall tower may be a C3 splitter split-wall tower. In embodiments, the position and number of partitions or split walls within the tower may be varied. In embodiments, partitions or split walls may be located in the middle or lower part of the single tower. In embodiments, two or more partitions may be provided, located at different heights in the single tower.

[0059] Figure 2 shows an example in which a partition plate may be included in the middle section of a divided wall tower.

[0060] As shown in Figure 2, scheme 200 may include a single divided-wall tower 202 comprising one or more trays 204 and partition plates or dividing walls 206. The partition plates or dividing walls 206 define a pre-distillation section 208 and a main distillation section 210.

[0061] In the embodiment, a single split-wall column 202 may be configured to separate the processed unsaturated LPG into four streams. In the embodiment, the four streams may include a light fraction stream, a PGP stream, a propane stream, and a C4+ stream.

[0062] In the embodiment, the processed unsaturated LPG feed stream 212 may be fed into the pre-distillation section 208 of the split-wall column 202. In the embodiment, a single split-wall column 202 may be configured to produce an overhead stream 214, a first side-draw stream 216, a second side-draw stream 218, and a bottom product stream 220.

[0063] In the embodiment, lighter compounds (e.g., ethane and ethylene) may be removed from the top of the column via an overhead stream 214. In the embodiment, removing lighter compounds may make it possible to meet the light fraction specification of the PGP. As illustrated, a single split-wall column 202 may include a condenser system 226. In the embodiment, the condenser system 226 may include one or more coolers or cooling systems, one or more pumps, and one or more reflux drums. In the embodiment, the condenser system 226 may be configured to include one or more recirculation lines configured to recirculate a portion 228 of the overhead stream 214. A portion 228 may be returned to the top of the single split-wall column 202, and another portion 230 may be sent to an exhaust gas system.

[0064] In the embodiment, the first side draw stream 216 may be located below the overhead stream 214. In the embodiment, the first side draw stream 216 may contain the PGP product stream. In the embodiment, the first side draw stream 216 may be located several trays 204 below the overhead stream 214. In the embodiment, the number of trays between the overhead stream 214 and the first side draw stream 216 should be sufficient to ensure the necessary separation of lighter compounds from the PGP product stream. In the embodiment, 3 to 9 trays 204 may be provided between the overhead stream 214 and the first side draw stream 216. For example, there may be 3, 4, 5, 6, 7, 8, 9 trays, or any range of trays defined by any two of these embodiments between the overhead stream 214 and the first side draw stream 216. In the embodiment, the PGP containing the first side draw stream 216 may be sent to the first storage unit 222.

[0065] In the embodiment, a second side draw stream 218 may be located below the first side draw stream 216. In the embodiment, the second side draw stream 218 may contain the propane component of the LPG feed. In the embodiment, the propane component is concentrated in the main fractionation section 210 of a single split-wall column 202. Therefore, in the embodiment, the second side draw stream 216 may be drawn from the main fractionation section 210 of the split-wall column 202. In the embodiment, the location of the side draw stream 216 may be an appropriate location along the main fractionation section 210 to obtain the required propane product purity. In the embodiment, the second side draw stream 218 may be sent to a second storage unit 224.

[0066] C4+ and heavier components can be removed from the segmented-wall column 202 via the bottom stream 220. In the embodiment, the segmented-wall column may include a reboiler system 342 that recirculates and returns the material to the column.

[0067] In the proposed scheme, the functions of a propane decontamination tower, an ethane decontamination tower, and a C3 splitter tower can be integrated into a single split-wall tower. This single-tower scheme can be more energy efficient than conventional schemes.

[0068] In the embodiment, a single partition wall tower may include multiple partition plates or partition walls. In the embodiment, partition plates or partition walls may be located at different heights within a single partition wall tower. In the embodiment, different partition plates or partition walls may at least partially overlap or be located at the same height within a single partition wall tower.

[0069] Figure 3 shows a scheme 300 including a partition wall tower 302. The partition wall tower 302 may include one or more trays 304, a first partition plate or partition wall 306, and a second partition plate or partition wall 308. As illustrated, the first partition plate or partition wall 306 and the second partition plate or partition wall 308 may be at different heights within a single partition wall tower 302. In the embodiment shown in Figure 3, the first partition plate or partition wall 306 may be located in the uppermost section or part of the partition wall tower, and the second partition plate 308 may be located in the middle of the partition wall tower 302. In the embodiment, the first partition plate or partition wall 306 may extend downward from the upper end of the partition wall tower 302. In the embodiment, as shown in the figure, the first partition plate or dividing wall 306 and the second partition plate or dividing wall 308 may at least partially overlap or be provided at the same height within a single dividing wall tower. In the embodiment, the second partition plate or dividing wall 308 does not reach the bottom end of the dividing wall tower 302. In the embodiment, the first partition plate or dividing wall 306 and the second partition plate or dividing wall 308 may define a pre-distillation section 310 and a main distillation section 312 within a single dividing wall tower 302.

[0070] In this embodiment, the processed LPG feed stream 314 may be passed through the pre-distillation section 310 of the split wall tower 302 to generate a first overhead stream 316, a second overhead stream 318, a side draw stream 320, and a bottom stream 322.

[0071] In the embodiment, as shown in Figure 3, the first overhead stream 316 and the second overhead stream 318 may be located on different sides of the top of the divided wall tower 302 defined by the first partition plate or dividing wall 306. For example, the first overhead stream 316 may be drawn from the top of the divided wall tower 302 on the first side of the first partition plate or dividing wall 306, and the second overhead stream 318 may be drawn from the top of the divided wall tower 302 on the second side of the first partition plate or dividing wall 306. In the embodiment, one overhead stream may contain light fractions (e.g., C2, e.g., ethane and / or ethylene), and the other overhead stream may contain PGP. In the illustrated embodiment, the first overhead stream 316 may contain light fractions, at least a portion of which may be sent to the exhaust gas system. In this example, the second overhead stream 318 may contain PGP, at least a portion of which may be sent to the first storage unit 324.

[0072] In the embodiment, a divided wall tower having a plurality of partition plates or dividing walls and including a first overhead stream and a second overhead stream may include a condenser system for each of the overhead streams. In the embodiment, each condenser system may include one or more condensers, a reflux drum, a pump, and a recirculation line. In the embodiment, a portion of the overhead stream may be recirculated to the divided wall tower. For example, as shown in Figure 3, the divided wall tower 302 may include a first condenser system 326 and a second condenser system 328. In the embodiment, the first overhead stream 316 may pass through the first condenser system 326. In the embodiment, the first condenser system 326 may include one or more recirculation lines 330 configured to recirculate at least a portion of the first overhead stream 316 to the divided wall tower 302. In the embodiment, at least a portion 332 of the first overhead stream 316 may be sent to an exhaust gas system. In the embodiment, the second overhead stream 318 may pass through the second condenser system 328. In the embodiment, the second condenser system 328 may include one or more recirculation lines 334 configured to recirculate at least a portion of the second overhead stream 318 to the split wall tower 302. In the embodiment, at least a portion 336 of the second overhead stream 318 may be sent to the first storage unit 324.

[0073] In the embodiment, the side draw stream 320 may be drawn from the main fractionation section of the split wall column 302. In the embodiment, the side draw stream 320 may be used to draw a propane product stream. In the embodiment, the side draw stream 320 may be provided at any location along the main fractionation section depending on the desired purity level. In the embodiment, the side draw stream 320 may be sent to a second storage unit 338.

[0074] In the embodiment, the bottom product stream 322 may contain C4+ and heavier products. In the embodiment, the bottom product stream 322 may be sent to a third storage unit 340. As shown in Figure 3, the split-wall column may include a reboiler system 342. The reboiler system may include a heater or heating system. In the embodiment, a portion of the bottom product stream may be withdrawn, passed through the reboiler system 342, and recirculated to the split-wall column 302.

[0075] In the embodiment, the condenser of one or more condenser systems may use a cooling medium or fluid (e.g., cooling water) to cool the overhead stream passing through it. In the embodiment, the heater or heating system of one or more reboilers may use a heating fluid or medium to heat the bottom product stream passing through it.

[0076] As previously mentioned with reference to Figures 2 and 3, the scheme described herein includes a single split-wall tower and can separate PGP from other components of the LPG supply more efficiently in terms of energy than conventional schemes that use multiple towers (e.g., three towers) in sequence to achieve the same level of separation. Therefore, the described scheme can help save site area.

[0077] In the embodiment, the described scheme may use only one condenser and one reboiler, compared to the conventional scheme in which each tower has its own condensation and reboil system. Therefore, this scheme may be less capital-intensive.

[0078] In the embodiments described herein, the total number of trays in the scheme may be less than the cumulative number of trays required in a conventional three-tower system. This also demonstrates that the segmented wall tower described herein is less capital-intensive.

[0079] In the examples, the scheme described may require lower reboiling and condensation loads than conventional three-column systems. In the examples, the reboiler load can be reduced by more than 10% compared to known three-column systems when using the system described herein. Thus, the scheme described herein may result in lower utility consumption and, consequently, lower operating costs.

[0080] In the embodiments, the system described herein, which includes a single segmented wall tower, may include one or more control systems, sensors, and other standard components that enable its control and operation.

[0081] In embodiments, although not shown, the systems described herein may include one or more sensors commonly used in the art. In embodiments, the sensors may be used to monitor the operation of the described systems. Non-limiting examples of one or more sensors may include temperature sensors, pressure sensors, flow meters, and other similar sensors.

[0082] In embodiments, although not shown, one or more control systems may include one or more controllers and / or other suitable computing devices to control one or more parts of the systems described herein. A control system may include any number of logical components, program components, and physical components. In embodiments, a controller may include one or more processors and memory coupled to communicate with one another. In embodiments, one or more input / output devices (e.g., monitors, keyboards, speakers, microphones, computer mice, etc.) may be coupled to one or more controllers. In embodiments, one or more controllers may include one or more communication elements, e.g., receivers, transmitters, transceivers, or similar structures that enable wired and / or wireless communication.

[0083] In the embodiment, memory associated with one or more controllers and / or other suitable computing devices may be a non-temporary computer-readable medium. Any suitable memory technology may be used to implement memory, such as static random-access memory (SRAM), synchronous dynamic RAM (SDRAM), non-volatile / flash memory, or any other type of memory capable of storing information.

[0084] In embodiments, memory may be used to store logic instructions (for example, one or more software modules, and / or other sufficient information for operation, safety procedures, and / or routine maintenance processes, without limit). In embodiments, logic instructions may be used to operate, control, and / or monitor the operation of the system and / or one or more of its subcomponents. In embodiments, memory may store an operating system and one or more software applications, instructions, programs, and / or data to implement the methods described herein and functions resulting from various systems. Any operation of the described systems may be implemented in hardware, software, or a combination thereof. In the context of software, operation means a computer executable instruction stored on one or more computer-readable storage media which, when executed by one or more processors, performs the operation described. Computer executable instructions may include programs, objects, routines, data structures, components, etc., that perform one or more functions or implement certain abstract data types.

[0085] As will be apparent to those skilled in the art, various modifications and alterations are possible without departing from the spirit or scope of this disclosure. Accordingly, this application is intended to encompass modifications and alterations of this disclosure insofar as they fall within the scope of the appended claims and their equivalents.

Claims

1. A process for recovering polymer-grade propylene from liquefied petroleum gas (LPG), To supply an LPG stream to the pre-distillation section of the split wall tower, The aforementioned segmented wall tower generates a polymer-grade propylene product stream and a propane product stream, Includes, The polymer-grade propylene product stream is obtained as an overhead stream or a side-draw stream. process.

2. The process according to claim 1, further comprising generating a light fraction stream and a C4+-containing stream.

3. The aforementioned light fraction stream is generated as an overhead stream. The polymer-grade propylene product stream is generated as a first side-draw stream. The aforementioned propane product stream is generated as a second side draw stream, The C4+-containing stream is generated as a bottom product stream. The process according to claim 2.

4. The process according to claim 3, wherein the first side draw stream is drawn from below the overhead stream, and the second side draw stream is drawn from below the first side draw stream.

5. The process according to claim 4, wherein the second side draw stream is extracted from the main fractional distillation section of the divided wall tower.

6. The aforementioned light fraction stream is generated as a first overhead stream, The polymer-grade propylene product stream is generated as a second overhead stream. The aforementioned propane product stream is generated as a side draw stream, The C4+-containing stream is generated as a bottom product stream. The process according to claim 2.

7. The process according to claim 6, wherein the drawstream is extracted from the main fractional distillation section of the divided wall tower.

8. The process according to claim 3 or 6, further comprising passing at least a portion of the bottom product stream through a reboiler and extracting the remainder.

9. The process according to claim 1, further comprising sending the polymer-grade propylene product stream to a first storage unit and the propane product stream to a second storage unit.

10. A segmented wall tower for producing polymer-grade propylene from liquefied petroleum gas (LPG), One or more dividing walls within the dividing wall tower, the dividing wall configured to define a pre-distillation section and a main distillation section within the dividing wall tower, An LPG feed is configured to be introduced in the aforementioned pre-distillation section, One or more overhead streams, One or more side draw streams including a propane product side draw stream extracted from the main fractional distillation section of the divided wall column, Bottom product stream and A reboiler system configured to heat at least a portion of the bottom product stream and recirculate it to the divided wall tower, A divided wall tower, including a

11. The divided wall tower according to claim 10, wherein the one or more divided walls include two divided walls arranged at different heights within the divided wall tower.

12. The divided wall tower according to claim 10 or 11, wherein at least one of the one or more divided walls extends downward from the upper end of the divided wall tower.

13. The divided wall tower according to claim 10, wherein one divided wall at least partially overlaps another divided wall.

14. The segmented wall tower according to claim 10, wherein the one or more overhead streams include an overhead stream of light fractions.

15. The segmented wall tower according to claim 10 or 14, wherein the one or more side draw streams further comprise propylene-grade polymer product streams drawn from below the one or more overhead streams.

16. The segmented wall tower according to claim 10, wherein the one or more overhead streams include a first overhead stream and a second overhead stream, and one of the first overhead stream or the second overhead stream includes a propylene-grade polymer product stream.

17. The segmented wall tower according to claim 10, further comprising a condenser system for each of the one or more overhead streams.

18. The segmented wall tower according to claim 17, further comprising an overhead recirculation line for each of the one or more overhead streams, wherein each overhead recirculation line is configured to recirculate at least a portion of each overhead stream.

19. A scheme for producing polymer-grade propylene from liquefied petroleum gas (LPG), It includes a single distillation column, the single distillation column is a divided wall column, and the divided wall column is One or more dividing walls within the dividing wall tower, the dividing wall configured to define a pre-distillation section and a main distillation section within the dividing wall tower, An LPG feed is configured to be introduced in the aforementioned pre-distillation section, One or more overhead streams, One or more side draw streams including a propane product side draw stream extracted from the main fractional distillation section of the divided wall column, Bottom product stream and including, Scheme.

Images