Treater Regeneration

Patent metadata

Field	Value
Publication number	US-2016361705-A1
Application number	US-201615044222-A
Country	US
Kind code	A1
Filing date	Feb 16, 2016
Priority date	Jun 11, 2015
Publication date	Dec 15, 2016
Grant date	—

Abstract

Disclosed are embodiments of a method of regenerating a desiccant in an off-line treater of a polyolefin production process. The method may include a heating phase followed by a cooling phase. The heating phase may involve use of a regenerating gas made from heating a treated a recycle stream of the polyolefin production process to regenerate desiccant in an off-line treater. The cooling phase may involve thermosyphoning the regenerating gas, nitrogen, an olefin-free diluent, or combinations thereof in a closed-convection loop of the off-line treater.

First claim

What is claimed is:

1 . A method for reducing NO emissions when regenerating a desiccant in an off-line treater comprising:
regenerating at least a portion of the desiccant in the off-line treater using a regenerating gas which comprises a treated recycle stream to yield a regenerating effluent stream comprising one or more impurities and the regenerating gas; and flaring the one or more impurities obtained from the regenerating effluent stream, wherein the step of flaring produces fewer of the NO emissions compared to a similar method which does not use the treated recycle stream in the regenerating gas.

2 . The method of claim 1 , wherein the treated recycle stream is obtained by treating a recycle stream of a polyolefin production process in an on-line treater.

3 . The method of claim 1 , wherein the off-line treater is one of 8 to 40 treaters in a polyolefin production process.

4 . The method of claim 1 , wherein the treated recycle stream comprises propane, butane, isobutane, pentane, isopentane, hexane, heptane, or a combination thereof.

5 . The method of claim 1 , further comprising:
flowing an impurity stream to a knockout pot before the step of flaring.

6 . A method of regenerating a desiccant in an off-line treater comprising:
regenerating at least a portion of the desiccant in the off-line treater using a regenerating gas which comprises a treated recycle stream from a polyolefin production process to yield a regenerating effluent stream.

7 . The method of claim 6 , wherein the treated recycle stream is obtained by treating a recycle stream of the polyolefin production process in an on-line treater.

8 . The method of claim 6 , wherein the treated recycle stream, the regenerating gas, and the regenerating effluent stream, each comprise diluent from the polyolefin production process.

9 . The method of claim 8 , wherein the regenerating gas and the regenerating effluent stream comprise the diluent in a gaseous phase.

10 . The method of claim 8 , wherein the treated recycle stream comprises the diluent in a liquid phase.

11 . The method of claim 8 , wherein the diluent is propane, butane, isobutane, pentane, isopentane, hexane, heptane, or combinations thereof.

12 . A desiccant regeneration system comprising:
an on-line treater treating a recycle stream from a polyolefin production process to yield a treated recycle stream; a heater receiving and heating at least a portion of the treated recycle stream to yield a regenerating gas; and an off-line treater receiving the regenerating gas and regenerating a desiccant in the off-line treater.

13 . The system of claim 12 , wherein the off-line treater comprises a closed-convection loop thermosyphoning the regenerating gas, nitrogen, or both and cooling the off-line treater during a cooling phase of desiccant regeneration.

14 . The system of claim 13 , wherein the closed-convection loop comprises a finned air cooler.

15 . The system of claim 12 , further comprising:
a regenerating effluent stream connected to the off-line treater; a separator separating the regenerating effluent stream into an impurity stream and a regenerating recycle stream; and a knockout pot receiving the impurity stream and recovering impurities, a flare receiving and flaring the impurities, wherein flaring the impurities produces fewer NO x emissions compared to a similar system which does not use the treated recycle stream to yield the regenerating gas.

16 . The system of claim 12 , further comprising:
a regenerating effluent stream connected to the off-line treater; wherein the heater is a cross exchanger which heats the at least a portion of the treated recycle stream using the regenerating effluent stream.

17 . The system of claim 16 , wherein the heater separates the regenerating effluent stream into an impurity stream and a regenerating recycle stream, the system further comprising:
a knockout pot receiving the impurity stream and recovering impurities, a flare receiving and flaring the impurities, wherein flaring the impurities produces fewer NO x emissions compared to a similar system which does not use the treated recycle stream to yield the regenerating gas.

18 . The system of claim 12 , wherein the off-line treater is one of a pair of feed treaters configured to treat a feed stream for the polyolefin production process when on-line, and wherein the pair of feed treaters is one pair of 4 to 20 pairs of feed treaters in the polyolefin production process.

19 . The system of claim 18 , wherein the on-line treater is a recycle treater configured to treat the recycle stream.

20 . The system of claim 12 , wherein the on-line treater and the off-line treater are a pair of recycle treaters configured to treat the recycle stream when on-line, and wherein the pair of recycle treaters are one pair of 4 to 20 pairs of recycle treaters in the polyolefin production process.

Assignees

• Chevron Phillips Chemical Co Lp

Inventors

• Romig Ralph W
• Mcelvain Robert R
• Page Steve E

Classifications

• B01D53/04

  with stationary adsorbents {(B01D53/025 takes precedence)} · CPC title

• B01D2259/4009

  using hot gas · CPC title

• B01D2259/40052

  Recycled product or process gas · CPC title

• B01D2253/108

  Zeolites · CPC title

• B01D2257/80

  Water · CPC title