System and process for producing polymer grade propylene from unsaturated LPG using single column

Abstract

A combined separation process and system for separating a high purity polymer grade propylene product from a liquefied petroleum gas stream. In an example, the systems and methods combine the functions of a dethanizing column and a depropanizing column with a C3 separation system to separate a high purity polymer grade propylene product from a liquefied petroleum gas stream, thereby eliminating the need for separate dethanizing columns, depropanizing columns, and C3 separation columns.

Description

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

[0003] This disclosure relates to a separation method and system. Specifically, a combined system and method can separate high-purity polymer-grade propylene products from liquefied petroleum gas streams. In examples, the system and method described combine the functions of a deethaner and a depropaner with a C3 separation system.

[0004] Discussion of related technologies

[0005] Polymer grade propylene (PGP) is a high-purity form of propylene, primarily used as a raw material for the production of polypropylene, one of the most widely used plastics. Polypropylene has a wide range of applications due to its versatility, durability, chemical resistance, and heat resistance. PGP has stringent specifications, and its purity requirements in industry range from 99.5% (by volume) to 99.8% (by volume).

[0006] PGP is typically recovered from liquefied petroleum gas (LPG). This method usually requires multiple sequential distillation columns to achieve high purity levels and optimal recovery of propylene from the treated unsaturated gas. Known systems employ two or three distillation columns. Two-column systems typically include a depropanizer followed by a C3 separator. Three-column systems typically include a depropanizer followed by an ethane separator, and then a C3 separator.

[0007] Figure 1A conventional multi-tower system 100 is shown. In the example shown, the scheme includes three distillation towers. As shown, the treated LPG stream 102 is fed to the multi-tower system, which includes a propane de-propane tower 110, a de-ethaner tower 120 downstream of the propane de-propane tower 110, and a C3 separation tower 130 downstream of the de-ethaner tower 120. As shown, each tower may include corresponding condenser and reboiler systems 116, 118, 126, 128, 136, and 138, respectively. The propane de-propane tower 110 is typically configured to remove propane and lighter components from the treated LPG stream. As shown, 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 propane de-propane tower 110. The overhead stream 112 of the depropanizer 110 is then typically fed to the deethanizer 120 to remove light fractions C2 (ethane and ethylene) via the overhead stream 122, a portion of which is directed to the effluent system. The C3-rich stream from the bottom product stream 124 of the deethanizer 120 is then fed to the C3 separator 130, which is configured to separate the PGP product from the propane product. As shown, the overhead stream 132 of the C3 separator 130 discharges the remaining light fractions and directs them to the effluent system. The side stream 140 is used to supply the PGP product stream, while the bottom product stream 134 of the C3 separator 130 supplies the propane product stream.

[0008] Despite their effectiveness, multi-tower systems require high capital investment and a large footprint due to the multiple towers and other auxiliary equipment. Furthermore, multi-tower systems tend to be less energy efficient due to remixing effects.

[0009] Therefore, there is a need for an improved system that can offer advantages over currently available methods and equipment. Summary of the Invention

[0010] Examples of systems and methods for producing PGP from unsaturated LPG using a single tower can essentially eliminate one or more problems caused by the limitations and drawbacks of the associated technologies, or at least provide a useful alternative for the public.

[0011] Compared to currently available systems, the examples described herein offer more energy-efficient systems and methods.

[0012] Compared to currently available examples, the examples described herein can lead to reduced capital investment.

[0013] Compared to currently available examples, the instance described in this article may require less floor space.

[0014] Additional features and advantages of the examples described herein will be set forth in the following description, and will be apparent in part from that description, or may be learned by practice of this disclosure. The objects and other advantages of this disclosure will be realized and attained by means of the structures particularly pointed out in the written description, the claims, and the drawings.

[0015] In an example, the method described herein may be a method for recovering polymer-grade propylene from liquefied petroleum gas (LPG), which may include feeding an LPG stream to a pre-fractionation section of a diaphragm column; and producing a polymer-grade propylene product stream and a propane product stream through the diaphragm column, wherein the polymer-grade propylene product stream may be obtained as a top stream or as a side-stream product stream.

[0016] In an example, the method may include producing a light distillate stream and a C4+-containing stream.

[0017] In this example, the light distillate fraction can be used as the overhead stream, the polymer-grade propylene product stream can be used as the first side-stream product stream, the propane product stream can be used as the second side-stream product stream, and the C4+-containing stream can be used as the bottom product stream.

[0018] In this example, the first side-line extraction flow can be extracted below the top flow, and the second side-line extraction flow can be extracted below the first side-line extraction flow.

[0019] In this example, the second side stream can be extracted from the main fractionation section of the diaphragm column.

[0020] In this example, the light distillate fraction can be used as the overhead stream of the first column, the polymer-grade propylene product stream can be used as the overhead stream of the second column, and the propane product stream can be used as a side-stream.

[0021] The C4+-containing stream can be used as the bottom product stream for production.

[0022] In this example, the outflow can be extracted from the main fractionation section of the diaphragm column.

[0023] In an example, the method may include sending at least a portion of the bottom product stream to a reboiler and extracting the remainder.

[0024] In an example, the method may include directing a polymer-grade propylene product stream to a first storage unit and a propane product stream to a second storage unit.

[0025] In this example, the present invention describes a baffled column for producing polymer-grade propylene from liquefied petroleum gas (LPG), the baffled column may include one or more baffles configured to define a pre-fractionation section and a main fractionation section within the baffled column; an LPG feed configured to be fed into the pre-fractionation section; one or more overhead streams; one or more side-stream feed streams, which may include a propane product side-stream feed stream from the main fractionation section of the baffled column; a bottom product stream; and a reboiler system configured to heat and recycle at least a portion of the bottom product stream back to the baffled column.

[0026] In an example, one or more partitions may include two partitions located at different heights within a partition tower.

[0027] In this example, at least one of one or more partitions may extend downwards from the top of the partition tower.

[0028] In this example, one partition may at least partially overlap with another partition.

[0029] In this example, one or more overhead streams may include overhead streams of light fractions.

[0030] In an example, one or more side-stream produced streams may include polymer-grade propylene product streams produced below one or more overhead streams.

[0031] In an example, one or more overhead streams may include a first overhead stream and a second overhead stream, wherein one of the first overhead stream or the second overhead stream may include a polymer-grade propylene product stream.

[0032] In an example, a baffled tower may include a condenser system for each of one or more overhead streams.

[0033] In an example, a diaphragm tower may include a top recirculation line for each of one or more top flow, each top recirculation line being configured to recirculate at least a portion of the respective top flow.

[0034] In this example, the present invention describes a scheme for producing polymer-grade propylene from liquefied petroleum gas (LPG), which may include a single distillation column, wherein the single distillation column is a baffle column, the baffle column may include one or more baffles within the baffle column and configured to define a pre-fractionation section and a main fractionation section within the baffle column; an LPG feed configured to be fed into the pre-fractionation section; one or more overhead streams; one or more side-stream feed streams, which may include a propane product side-stream feed stream from the main fractionation section of the baffle column; and a bottom product stream.

[0035] Any combination of the features listed above may be implemented without departing from the spirit or scope of this 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 this disclosure as requested. Attached Figure Description

[0036] The accompanying drawings, which are included to provide a further understanding of this disclosure and are incorporated in and form part of this specification, illustrate embodiments of this disclosure and, together with the description, serve to explain the principles of this disclosure.

[0037] In the attached diagram:

[0038] Figure 1 A conventional system for producing PGP by fractionating LPG fluid using a deethaner, a depropanizer, and a C3 separator, as is currently available in the art, is described.

[0039] Figure 2 and Figure 3 Examples of exemplary systems and methods for fractionating LPG fluids according to this disclosure are described. Detailed Implementation

[0040] In this example, a method and system for recovering PGP from LPG are disclosed. In this example, the method and system may include a scheme with a single tower that can achieve the same PGP recovery rate, quality, and high purity as that achieved by sequential operation of multiple towers. As previously stated, high purity of PGP refers to a purity of at least 99% (volume), for example, from about 99.5% (volume) to about 99.8% (volume). In this example, the single tower may include a diaphragm tower.

[0041] In examples, the single-tower scheme described herein offers significant advantages compared to conventional sequential distillation columns for producing high-purity propylene from LPG. As used herein, the term "single" to refer to the column in the scheme described herein is intended to mean that the scheme does not include any other distillation columns for distilling PGP from the LPG feed stream. In examples, the single-tower scheme described herein may require less energy and less capital investment, and / or less floor space compared to conventional schemes. In examples, this scheme can separate PGP from all other components using a single column, while conventional schemes may employ three sequential columns to achieve the same level of separation. Therefore, the present invention contributes to saving floor space. In examples, compared to conventional schemes where each column in a multi-tower system typically includes its own condenser and reboiler system, the scheme described herein may employ only one condenser and reboiler. Therefore, the scheme described herein can be less capital-intensive. In examples, the total number of trays in the scheme described herein can be less than the cumulative number of trays required in a conventional three-tower system. Therefore, the scheme described herein can be less capital-intensive than a multi-tower system. Furthermore, in the examples described herein, the approach may require less reboiling and condensation load than a conventional three-tower system, which translates to lower utility consumption and therefore lower operating costs.

[0042] In examples, a single column may include a fractionating column. As used herein, the term "fractionating column" can refer to any system, apparatus, or combination of systems and / or apparatuses suitable for the selective separation of mixtures containing two or more components with different boiling points. In examples, a fractionating column may include a distillation column, a rectification column, a stripping column, a separation column, etc.

[0043] In examples, a single column may include a partitioned column, i.e., a column comprising one or more partitions. In examples, a single column may include a fractionating column having one or more partitions disposed therein. For the purposes of this specification, a partitioned column refers to a column comprising a “partition”, which means any partition plate disposed within the internal space of the column to provide different sections within the column. In examples, partitions in a partitioned column may divide the internal space of the partitioned column to provide a first fractionating section or pre-fractionating section on one side of the plate and a second fractionating section or main fractionating section on the other side of the plate. The partitions may be segmented or continuous. The partitions may be parallel or non-parallel relative to the longitudinal axis of the column. The first and second fractionating sections may have the same or different cross-sectional areas, volumes, or both. In one or more specific embodiments, the column may have a circular cross-section, and the partitions may equally divide the cross-section of the column to provide equal cross-sectional areas within the first and second fractionating sections. In examples, a stripping zone may exist at least below the pre-fractionating section.

[0044] In this example, a single tower may include one partition or baffle. In this example, a single tower may include more than one partition or baffle, such as two partitions or baffles. In this example, the partition or baffle may be located at the bottom, middle, or top of the single tower. In this example, the partition or baffle may extend across more than one section of the single tower. In this example, where the single tower includes more than one partition or baffle, the partitions or baffles may be located at different heights within the single tower.

[0045] In this example, the treated LPG stream can be received in the pre-fractionation section of a baffled column, where multiple hydrocarbon components are separated by distillation. The baffles in the baffled column can be configured to restrict the mixing of fluids (which may include different compositions) on both sides of the baffle. In this example, this can make the distillation process more energy efficient.

[0046] In this example, the baffle column can be configured to separate the treated unsaturated LPG into multiple streams. In another example, the baffle column can 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.

[0047] In this example, the light distillate may include lighter compounds such as ethane and ethylene. In this example, the light distillate may be removed from the top of the column. In this example, the removal of the light distillate may help meet the PGP's light fraction specifications.

[0048] In this example, PGP can be drawn through a first side-stream outlet located several trays below the top tray of the column. In this example, the trays between the top stream and the PGP outlet help ensure the desired separation of light fractions from the PGP product. In this example, the first side-stream product stream can be recovered as the main product and directed to a first storage unit.

[0049] In this example, propane can be concentrated in the main fractionation section of a partitioned column. In this example, a second side-stream product is extracted from a suitable location below the first side-stream outlet to produce a propane product stream. In this example, the second side-stream product stream can be directed to a second storage unit.

[0050] In this example, the C4+ component can be collected as a bottom product stream from the bottom of the main fractionation section of the diaphragm column. In this example, at least a portion of the bottom product stream from the main fractionation of the diaphragm column can be sent to a reboiler and recycled back to the diaphragm column. In this way, heat transfer to the bottom of the diaphragm column is possible. In this example, the remaining portion of the bottom product stream not sent to the reboiler can be extracted as a bottom product.

[0051] In this way, the functions of a propane stripper, an ethane stripper, and a C3 separation tower (typically found in multi-tower configurations) can be integrated into a single baffle tower in the methods and systems described herein. This single-tower configuration can be more energy efficient than conventional multi-tower configurations.

[0052] The following will be described in detail with reference to one or more examples illustrated in the accompanying drawings.

[0053] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this disclosure pertains. Unless otherwise stated, all patents, patent applications, published applications and publications, websites and other published materials mentioned throughout this disclosure are incorporated herein by reference in their entirety. Where a term has multiple definitions herein, the definition in this section shall prevail. In the reference to URLs or other such identifiers or addresses, it should be understood that such identifiers may change and information on the Internet may vary, but equivalent information can be found by searching the Internet. References to them demonstrate the availability and public dissemination of such information.

[0054] As used herein, unless the context clearly indicates otherwise, the singular forms “a / an” and “the” may contain plural references.

[0055] As used herein, the terms first, second, third, etc., can describe various elements, components, regions, layers, and / or segments, which should not be limited by these terms. These terms may be used only to distinguish one element, component, region, layer, or segment from another. Terms such as “first,” “second,” and other numerical terms used herein do not imply order or sequence unless the context clearly indicates otherwise. Therefore, without departing from the teachings of the exemplary embodiments, the first element, component, region, layer, or segment discussed below may be referred to as a second element, component, region, layer, or segment.

[0056] As used herein, ranges and quantities can be expressed as “about” a specific value or range. “About” also includes precise quantities. Thus, “about 5%” means about 5% other than 5%. The term “about” means within the typical experimental error expected for the intended application or purpose.

[0057] As used herein, “and / or” includes any and all combinations of one or more of the associated enumerated items.

[0058] As used in this article, "combination" refers to any association between two or more items. Association can be spatial or refers to using two or more items for a common purpose.

[0059] As used herein, “includes” and “contains” are intended to be interpreted openly as meaning “including but not limited to” and “includes but not limited to”, respectively, thus including not only the elements described but also any additional elements.

[0060] As used herein, "optional" or "optionally" means that an event or condition described below may or may not occur, and the description includes instances where the event or condition occurs and instances where it does not occur. For example, an optional component in a system means that the component may or may not exist in the system.

[0061] As used in this article, “generally” means “mostly but not entirely in accordance with the specification”.

[0062] Figure 2 and Figure 3 An example of a single-tower scheme as described herein is shown. In this example, the functions of a deethaner, a depropanizer, and a C3 separation tower are integrated into a single partitioned tower for PGP production. In this example, the single partitioned tower can be a C3 separation partitioned tower. In this example, the position and number of partitions or baffles within the tower can be modified. In this example, the partitions or baffles can be located in the middle or lower part of the single tower. In this example, two or more partitions can be located at different heights within the single tower.

[0063] Figure 2 An example is shown where a partition tower may include partitions within its central section.

[0064] like Figure 2 As shown, scheme 200 may include a single partitioned column 202, which includes one or more trays 204 and partitions or baffles 206 that define the pre-fractionation section 208 and the main fractionation section 210.

[0065] In this example, a single baffle column 202 can be configured to separate the treated unsaturated LPG into four streams. In this example, the four streams may include a light fraction stream, a PGP stream, a propane stream, and a C4+ stream.

[0066] In this example, the treated unsaturated LPG feed stream 212 can be fed into the pre-fractionation section 208 of the diaphragm column 202. In this example, a single diaphragm column 202 can be configured to produce a top stream 214, a first side stream 216, a second side stream 218, and a bottom product stream 220.

[0067] In this example, lighter compounds such as ethane and ethylene can be removed from the top of the column via overhead stream 214. In this example, by removing lighter compounds, it is possible to meet the light fraction specifications of the PGP. As shown, a single diaphragm column 202 may include a condenser system 226. In this example, the condenser system 226 may include one or more coolers or cooling systems, one or more pumps, and one or more reflux tanks. In this example, the condenser system 226 may be configured to include one or more recirculation lines that form a portion 228 of the recirculation column overhead stream 214 (which is directed back to the top of the single diaphragm column 202), while another portion 230 may be directed to an exhaust gas system.

[0068] In this example, the first side-stream feed 216 may be below the overhead feed 214. In this example, the first side-stream feed 216 may include the PGP product stream. In this example, the first side-stream feed 216 may be located several trays 204 below the overhead feed 214. In this example, the number of trays between the overhead feed 214 and the first side-stream feed 216 should be sufficient to ensure the desired separation of lighter compounds from the PGP product stream. In this example, 3 to 9 trays 204 should be positioned between the overhead feed 214 and the first side-stream feed 216 stream. For example, there may be 3, 4, 5, 6, 7, 8, or 9 trays, or any range of trays defined by any two of these examples, between the overhead feed 214 and the first side-stream feed 216 stream. In this example, the PGP containing the first side-stream feed 216 may be directed to the first storage unit 222.

[0069] In this example, the second side-stream outflow 218 may be located below the first side-stream outflow 216. In this example, the second side-stream outflow 218 may contain the propane component of the LPG feed. In this example, the propane component is concentrated in the main fractionation section 210 of a single partition column 202. Therefore, in this example, the second side-stream outflow 216 can be drawn from the main fractionation section 210 of the partition column 202. In this example, the side-stream outflow 216 may be positioned appropriately along the main fractionation section 210 to obtain the desired propane product purity. In this example, the second side-stream outflow 218 may be directed to a second storage unit 224.

[0070] C4+ and heavier components can be extracted from the baffle column 202 via the bottom stream 220. In this example, the baffle column may include a reboiler system 342 that is recycled back into the column.

[0071] In the proposed scheme, the functions of the propane stripper, ethane stripper, and C3 separation tower can thus be integrated into a single baffle tower. This single-tower scheme can achieve higher energy efficiency than conventional schemes.

[0072] In this example, a single partition tower may include multiple partitions or baffles. In this example, the partitions or baffles may be arranged at different heights within the single partition tower. In this example, different partitions or baffles may at least partially overlap or be at the same height within the single partition tower.

[0073] Figure 3 The diagram illustrates scheme 300, which includes a partition tower 302. This partition tower may include one or more trays 304, a first partition plate or baffle 306, and a second partition plate or baffle 308. As shown, the first partition plate or baffle 306 and the second partition plate or baffle 308 may be located at different heights within a single partition tower 302. Figure 3 In the illustrated example, the first partition plate or baffle 306 may be located in the top section or part of the baffle tower, and the second partition plate 308 may be located in the central portion of the baffle tower 302. In the example, the first partition plate or baffle 306 may extend downwards from the top of the baffle tower 302. In the example, as shown, the first partition plate or baffle 306 and the second partition plate or baffle 308 may at least partially overlap or be located at the same height within a single baffle tower. In the example, the second partition plate or baffle 308 does not reach the bottom of the baffle tower 302. In the example, the first partition plate or baffle 306 and the second partition plate or baffle 308 may define a pre-fractionation section 310 and a main fractionation section 312 within a single baffle tower 302.

[0074] In this example, the treated LPG feed stream 314 can be sent to the pre-fractionation section 310 of the diaphragm column 302 to produce a first overhead stream 316, a second overhead stream 318, a side stream 320, and a bottom stream 322.

[0075] In an example, such as Figure 3 As shown, the first overhead stream 316 and the second overhead stream 318 can be located on different sides of the top of the partitioned column 302 as defined by the first partition plate or baffle 306. For example, the first overhead stream 316 can be drawn from the top of the partitioned column 302 at a first side of the first partition plate or baffle 306, while the second overhead stream 318 can be drawn from the top of the partitioned column 302 at a second side of the first partition plate or baffle 306. In an example, one overhead stream may contain light fractions such as C2, for example ethane and / or ethylene, while the other overhead stream may contain PGP. In the example shown, the first overhead stream 316 may contain light fractions, at least a portion of which can be directed to the exhaust gas system. In an example, the second overhead stream 318 may contain PGP, at least a portion of which can be directed to the first storage unit 324.

[0076] In this example, a baffled tower having multiple baffles or partitions and including a first overhead flow and a second overhead flow may include a condenser system for each of the overhead flows. In this example, each condenser system may include one or more condensers, a reflux tank, a pump, and a recirculation line. In this example, a portion of the overhead flow may be recirculated to the baffled tower. For example, as... Figure 3 As shown, the baffle tower 302 may include a first condenser system 326 and a second condenser system 328. In one example, the first tower overhead flow 316 may pass through the first condenser system 326. In one example, the first condenser system 326 may include one or more recirculation lines 330 configured to recirculate at least a portion of the first tower overhead flow 316, which may be recirculated to the baffle tower 302. In one example, at least a portion 332 of the first tower overhead flow 316 may be sent to an exhaust gas system. In one example, the second tower overhead flow 318 may pass through the second condenser system 328. In one example, the second condenser system 328 may include one or more recirculation lines 334 configured to recirculate at least a portion of the second tower overhead flow 318 to the baffle tower 302. In one example, at least a portion 336 of the second tower overhead flow 318 may be sent to a first storage unit 324.

[0077] In this example, the side stream 320 can be drawn from the main fractionation section of the diaphragm column 302. In this example, the side stream 320 can be used to draw out the propane product stream. In this example, the side stream 320 can be located anywhere along the main fractionation section, depending on the desired purity level. In this example, the side stream 320 can be directed to the second storage unit 338.

[0078] In this example, the bottom product stream 322 may contain C4+ and heavier products. In this example, the bottom product stream 322 may be directed to the third storage unit 340. For example... Figure 3 As shown, the partition column may include a reboiler system 342. The reboiler system may include a heater or heating system. In this example, a portion of the bottom product stream may be collected and passed through the reboiler system 342 and recycled back to the partition column 302.

[0079] In one example, the condensers of one or more condenser systems may use a cooling medium or fluid (such as cooling water) to cool the overhead stream passing through them. In another example, the heaters or heating systems of one or more reboilers may use a heating fluid or medium to heat the bottom product stream passing through them.

[0080] In the example, as referred to above Figure 2 and Figure 3The aforementioned approach, as described herein, may include a single baffled tower to more energy-efficiently separate PGP from other components of the LPG feed compared to conventional approaches that use multiple sequential towers (e.g., three towers) to achieve the same level of separation. Therefore, the approach described herein can help save floor space.

[0081] In this example, compared to the conventional approach where each tower has its own condenser and reboiler system, the proposed approach can utilize only one condenser and one reboiler. Therefore, this approach can be less capital-intensive.

[0082] In the example, the total number of trays in the scheme described in this paper can be less than the cumulative number of trays required in a conventional three-tower system. This also demonstrates that diaphragm towers, as described in this paper, are less capital-intensive.

[0083] In this example, the solution described herein may require less reboiler and condenser load than a conventional three-tower system. In this example, the reboiler load can be reduced by more than 10% compared to known three-tower systems. Therefore, the solution described herein exhibits lower utility consumption and thus lower operating costs.

[0084] In the examples described herein, a system comprising a single diaphragm tower may include one or more control systems, sensors, and other standard components that allow it to be controlled and operated.

[0085] In the examples, although not shown, the systems described herein may include one or more sensors as commonly used in the art. In the examples, the sensors may be used to monitor the operation of the system. Non-limiting examples of one or more sensors may include temperature sensors, pressure sensors, flow meters, and other similar sensors.

[0086] In the examples, although not shown, one or more control systems may include one or more controllers and / or other suitable computing devices that can be used to control one or more parts of the system described herein. The control system may include any number of logical components, program components, and physical components. In the examples, the controller may include one or more processors and memories communicatively connected to each other. In the examples, one or more input / output devices (such as displays, keyboards, speakers, microphones, computer mice, etc.) may be connected to one or more controllers. In the examples, one or more controllers may include one or more communication elements (such as receivers, transmitters, transceivers, or similar structures) to enable wired and / or wireless communication.

[0087] In this example, the memory associated with one or more controllers and / or other suitable computing devices may be a non-volatile computer-readable medium. The memory may be implemented using any suitable memory technology, 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.

[0088] In this example, the memory may be used to store logical instructions, including but not limited to one or more software modules and / or other sufficient information for operation, security procedures, and / or routine maintenance processes. In this example, the logical instructions may be used to operate, control, and / or monitor the operation of the system and / or one or more of its subcomponents. In this example, the memory may store an operating system and one or more software applications, instructions, programs, and / or data to implement the methods described herein and the functions attributable to the various systems. Any operation of the system may be implemented in hardware, software, or a combination thereof. In the context of software, an operation refers to computer-executable instructions stored on one or more computer-readable storage media that perform the operation when executed by one or more processors. Computer-executable instructions may include programs, objects, routines, data structures, components, etc., that perform one or more functions or implement a particular abstract data type.

[0089] It will be apparent to those skilled in the art that various modifications and variations can be made without departing from the spirit or scope of this disclosure. Therefore, this application is intended to cover modifications and variations of this disclosure that fall within the scope of the appended claims and their equivalents.

Claims

1. A method for recovering polymer-grade propylene from liquefied petroleum gas (LPG), comprising: The LPG stream is fed into the pre-fractionation section of the diaphragm column; as well as The diaphragm tower produces a polymer-grade propylene product stream and a propane product stream. The polymer-grade propylene product stream is obtained as either the overhead stream or the side stream.

2. The method according to claim 1, further comprising producing a light distillate stream and a C4+-containing stream.

3. The method according to claim 2, wherein: The light distillate fraction is produced as the overhead stream from the column. The polymer-grade propylene product stream is produced as the first side-stream outflow. The propane product stream is produced as a second side-stream outflow, and The C4+-containing stream is produced as the bottom product stream of the tower.

4. The method of claim 3, wherein the first side-stream extract is extracted below the top stream, and the second side-stream extract is extracted below the first side-stream extract.

5. The method of claim 4, wherein the second side stream is drawn from the main fractionation section of the diaphragm tower.

6. The method according to claim 2, wherein: The light distillate fraction is produced as the overhead stream of the first column. The polymer-grade propylene product stream is produced as the overhead stream of the second tower. The propane product stream is produced as a side-stream produced stream, and The C4+-containing stream is produced as the bottom product stream of the tower.

7. The method of claim 6, wherein the extracted stream is extracted from the main fractionation section of the diaphragm tower.

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

9. The method of claim 1, further comprising directing the polymer-grade propylene product stream to a first storage unit and directing the propane product stream to a second storage unit.

10. A baffled tower for producing polymer-grade propylene from liquefied petroleum gas (LPG), comprising: One or more baffles are located in the baffled column and configured to define a pre-fractionation section and a main fractionation section within the baffled column; LPG feed, configured to input LPG feed in the pre-fractionation section; One or more tower top flows; One or more side streams, including a propane product side stream from the main fractionation section of the diaphragm column; Product flow at the bottom of the tower; as well as A reboiler system configured to heat at least a portion of the bottom product stream and recycle it to the diaphragm column.

11. The partition tower of claim 10, wherein the one or more partitions comprise two partitions located at different heights within the partition tower.

12. The partition tower according to claim 10 or 11, wherein at least one of the one or more partitions extends downward from the top of the partition tower.

13. The partition tower of claim 10, wherein one partition at least partially overlaps with the other partition.

14. The diaphragm column of claim 10, wherein the one or more overhead streams comprise overhead streams of light distillates.

15. The diaphragm tower according to claim 10 or 14, wherein the one or more side streams further comprise a polymer-grade propylene product stream drawn below the one or more overhead streams.

16. The partition tower of claim 10, wherein the one or more overhead streams comprise a first overhead stream and a second overhead stream, wherein one of the first overhead stream or the second overhead stream comprises a polymer-grade propylene product stream.

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

18. The diaphragm tower of claim 17, further comprising a top recirculation line for each of the one or more top flow, each top recirculation line configured to recirculate at least a portion of the respective top flow.

19. A method for producing polymer-grade propylene from liquefied petroleum gas (LPG), comprising: A single distillation column, wherein the single distillation column is a baffle column, the baffle column comprising: One or more baffles are located in the baffled column and configured to define a pre-fractionation section and a main fractionation section within the baffled column; LPG feed, configured to input LPG feed in the pre-fractionation section; One or more tower top flows; One or more side-stream outflows, including a propane product side-stream outflow from the main fractionation section of the diaphragm column; and Product flow at the bottom of the tower.

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