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EP-4739415-A1 - SYSTEM AND METHOD TO PRODUCE POLYMER GRADE PROPYLENE FROM UNSATURATED LPG USING A SINGLE COLUMN

EP4739415A1EP 4739415 A1EP4739415 A1EP 4739415A1EP-4739415-A1

Abstract

A separation process and system to separate highly pure polymer grade propylene product from a liquefied petroleum gas stream combined. In examples, the system and method as combine the functions of a deethanizer and of a depropanizer, with a C3 splitter system to separate highly pure polymer grade propylene product from a liquefied petroleum gas stream, thus eliminating the need for separate dethanizer, depropanizer, and C3-splitter.

Inventors

  • RANJAN, RAJEEV

Assignees

  • Kellogg Brown & Root LLC

Dates

Publication Date
20260513
Application Date
20240703

Claims (19)

  1. 1. A process for recovery of polymer grade propylene from liquified petroleum gas (LPG) comprising: feeding and LPG stream to a pre-fractionating section of a dividing wall column; and producing by the dividing wall column a polymer grade propylene product stream and a propane product stream, wherein, the polymer grade propylene product stream is obtained as an overhead stream or as a side draw stream.
  2. 2. The process of claim 1, further comprising producing a light ends stream and a C4+ containing stream.
  3. 3. The process of claim 2, wherein: the light ends stream is produced as an overhead stream, the polymer grade propylene product stream is produced is a first side draw stream, the propane product stream is produced as a second side draw stream, and the C4+ containing stream is produced as a bottoms product stream.
  4. 4. The process of claim 3. wherein the first side draw stream is drawn below the overhead stream, and the second side draw stream is drawn below the first side draw stream.
  5. 5. The process of claim 4, wherein the second side draw stream is drawn from a main fractionation section of the dividing wall column.
  6. 6. The process of claim 2, w herein: the light ends stream is produced as a first overhead stream, the polymer grade propylene product stream is produced is a second overhead stream, the propane product stream is produced as a side draw 7 stream, and the C4+ containing stream is produced as a bottoms product stream.
  7. 7. The process of claim 6, wherein the draw stream is drawn from a main fractionation section of the dividing w all column.
  8. 8. The process of claim 3 or 6, further comprising passing at least a portion of the bottoms product stream to reboiler and extracting the remaining portion.
  9. 9. The process 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. 10. A dividing wall column for production of polymer grade propylene from Liquified Petroleum Gas (LPG) comprising: one or more dividing walls in the dividing wall column and configured to define a pre-fractionating section and a main fractionation section inside the dividing wall column; an LPG feed configured to input LPG feed at the pre-fractionating section: one or more overhead streams; one or more side draw streams comprising a propane product side draw stream drawn from the main fractionationsection of the dividing wall column; a bottoms product stream; and a reboiler system configured to heat and recycle to the dividing wall column at least a portion of the bottoms product stream.
  11. 11. The dividing wall column of claim 10, wherein the one or more dividing walls comprise two dividing walls located at different heights within the dividing wall column.
  12. 12. The dividing wall column of claims 10 or 11, wherein at least one of the one or more dividing walls extends down from a top end of the dividing wall column.
  13. 13. The dividing wall column of claim 10, wherein one dividing wall at least partially overlaps with another dividing wall.
  14. 14. The dividing wall column of claim 10, wherein the one or more overhead streams comprises an overhead stream of light ends.
  15. 15. The dividing wall column of claim 10 or 14. wherein the one or more side draw streams further comprises a propylene grade polymer product stream drawn below the one or more overhead streams.
  16. 16. The dividing wall column of claim 10, wherein the one or more overhead streams comprises a first overhead stream and a second overhead stream, wherein one of the first overhead stream or the second overhead stream comprises a propylene grade polymer product stream.
  17. 17. The dividing wall column of claim 10, further comprising a condenser system for each overhead stream of the one or more overhead streams.
  18. 18. The dividing wall column of claim 17, further comprising an overhead recycle line for each of the one or more overhead streams, each overhead recycle line configured to recycle at least a portion of the respective overhead stream.
  19. 19. A scheme for producing polymer grade propylene from Liquified Petroleum Gas (LPG) comprising: a single distillation column, wherein the single distillation column is a dividing wall column comprising: one or more dividing walls in the dividing wall column and configured to define a pre-fractionating section and a main fractionation section inside the dividing wall column; an LPG feed configured to input LPG feed at the pre-fractionating section; one or more overhead streams; one or more side draw streams comprising a propane product side draw stream drawn from the main fractionation section of the dividing wall column; and a bottoms product stream.

Description

SYSTEM AND METHOD TO PRODUCE POLYMER GRADE PROPYLENE FROM UNSATURATED LPG USING A SINGLE COLUMN [0001] This application claims the benefit of Indian Patent Application No. IN202311045057, filed on July 5, 2023, which is hereby incorporated by reference for all purposes as if fully set forth herein. BACKGROUND Field of the Disclosure [0002] The present disclosure relates to a separation process and system. In particular, the system and method may separate highly pure polymer grade propylene product from a liquefied petroleum gas stream combined. In examples, the system and method as described combine the functions of a deethanizer column and of a depropanizer column, with a C3 splitter system. Discussion of the Related Art [0003] Polymer grade propylene (PGP) is a high-purity form of propylene primarily used as a feedstock in the production of polypropylene, which is one of the most widely used plastics. Polypropylene has various applications due to its versatility, durability, and resistance to chemicals and heat. The PGP has stringent specifications and its purity requirement in the industry varies from 99.5%(vol) to 99.8%(vol). [0004] PGP is generally recovered from liquefied petroleum gas (LPG). The process typically requires multiple sequential distillation columns to achieve the high-purity level and optimum recovery of propylene from treated unsaturated gas. Known systems employ two or three distillation columns. A two-column system typically includes a depropanizer column followed by a C3-splitter column. A three-column system ty pically includes a depropanizer column, followed by a dethanizer column, followed by a C3-splitter column. [0005] FIG. 1 illustrates a conventional multiple column system 100. In the illustrated example, the scheme includes three distillation columns. As shown, a treated LPG stream 102 is fed to a multiple distillation columns system including a depropanizer column 110, a deethanizer column 120 downstream the depropanizer column 110, and a C3-splitter column 130 downstream the deethanizer column 120. As illustrated, each column may include respective condenser and reboiler systems 116, 118, 126, 128, 136, and 138 respectively. The depropanizer column 110 is typically configured to remove propane and lighter for the treated LPG stream. As shown, a product stream of C4 (butane and butenes) and higher hydrocarbons if present (collectively referred to as “C4+”), may be removed as a bottoms product stream 114 of depropanizer column 110. The overhead stream 112 of the depropanizer column 1 10 is then typically fed to the deethanizer column 120 to remove the light ends C2 (ethane and ethylene) via overhead stream 122 with a portion being directed to an off-gas system. The C3-rich stream from the bottoms product stream 124 of the deethanizer column 120 is instead fed to a C3-splitter column 130 that is configured to separate the PGP product from the propane product. As illustrated, the overhead stream 132 of C3 -splitter column 130 will exhaust the remaining light ends and direct them to an off-gas system. A side draw 140 is used to provide a PGP product stream, while the botoms product stream 134 of C3-spliter column 130 provides a propane product stream. [0006] Although effective, multiple column systems require high capital investments and require large plot spaces because of the multiple columns and other ancillary7 equipment. Also, multiple column system tend to be energy inefficient due to the remixing effect. [0007] Thus, there is a need for improved systems that can provide advantages over the processes and equipment currently available. SUMMARY [0008] Examples of system and method to produce PGP from unsaturated LPG using a single column can substantially obviates one or more of the problems due to limitations and disadvantages of the related art or at least to provide the public with a useful alternative. [0009] Examples as described herein can provide a more energy efficient system and method as compared to what is currently available. [0010] Examples as described herein can lead to reduced capital investment as compared to what is currently available. [0011] Examples as described herein can require lesser plot space as compared to what is currently available. [0012] Additional features and advantages of the examples as described herein will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the disclosure. The objectives and other advantages of the disclosure will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. [0013] In examples, described herein may be a process for recovery7 of polymer grade propylene from liquified petroleum gas (LPG) that may include feeding and LPG stream to a pre-fractionating section of a dividing wall column; and producing by the dividing wall column a polymer gra