Recovery of ethylene from methanol to olefins process

Patent metadata

Field	Value
Publication number	US-10011541-B2
Application number	US-201615233009-A
Country	US
Kind code	B2
Filing date	Aug 10, 2016
Priority date	Nov 15, 2012
Publication date	Jul 3, 2018
Grant date	Jul 3, 2018

Abstract

Olefins may be recovered from a methanol to olefins reactor effluent by initially feeding the effluent to an absorber demethanizer to contact the effluent with an absorbent to recover an overheads including methane and ethylene and a bottoms including the absorbent, ethylene, and ethane. The bottoms are separated to recover an ethylene fraction and an ethane fraction. The overheads are cooled and partially condensed in a first heat exchanger to a temperature of −40° C. or greater. The resulting stream, or a portion thereof, may be further cooled and condensed via indirect heat exchange with a mixed refrigerant to a temperature of less than −40° C. The non-condensed vapors are separated from the condensed liquids to form a liquid fraction and a methane fraction. The liquid fraction is fed to the absorber demethanizer as reflux, and the methane and ethane fractions combined to form the mixed refrigerant.

First claim

What is claimed is:

1. A system for the conversion of methanol to olefins and recovery of the olefins, the system comprising:
a methanol-to-olefins reactor system for converting methanol to a reactor effluent comprising methane, ethylene, and ethane;
an absorber demethanizer for contacting at least a portion of the reactor effluent with an absorbent and to recover an overheads vapor fraction comprising methane and ethylene and a bottoms fraction comprising the absorbent, ethylene, and ethane;
one or more extractive distillation and/or distillation stages for separating the bottoms fraction to recover an ethylene fraction and an ethane fraction;
a first heat exchanger for cooling and partially condensing the overheads vapor fraction to a temperature of about −40° C. or greater;
a second heat exchanger for cooling and partially condensing at least a portion of the cooled and partially condensed overhead vapor fraction via indirect heat exchange with a mixed refrigerant, to a temperature of less than about −40° C.;
a separator for separating non-condensed vapors from the liquids condensed in the first and second heat exchangers to form an overhead liquid fraction and a methane fraction;
a flow line for feeding the overhead liquid fraction to the absorber demethanizer as a reflux;
a flow line, vessel, or mixing chamber for combining at least a portion of the methane and ethane fractions to form the mixed refrigerant.

2. The system of claim 1 , further comprising a caustic solution treatment system or an amine absorption system for removing carbon dioxide from the methanol-to-olefins reactor effluent or a portion thereof.

3. The system of claim 2 , further comprising a compressor for compressing the methanol-to-olefins reactor effluent upstream of the caustic solution treatment system or the amine absorption system.

4. The system of claim 1 , further comprising a molecular sieve dryer or a dehydration system for removing water from the methanol-to-olefins reactor effluent or a portion thereof.

5. The system of claim 1 , further comprising a heat exchanger for cooling the methanol-to-olefins reactor effluent upstream of the absorber demethanizer.

6. The system of claim 1 , further comprising:
a feed drum for splitting the methanol-to-olefins reactor effluent into a feed vapor stream and a feed liquid stream;
a flow line for supplying the feed vapor stream to an upper portion of the absorber demethanizer; and
a flow line for supplying the feed liquid stream to a lower portion of the absorber demethanizer.

7. The system of claim 1 , further comprising a side draw, a heat exchanger, and a return line for withdrawing a stream from, cooling, and returning the stream to the absorber demethanizer.

8. The system of claim 1 , wherein the second heat exchanger comprises a brazed aluminum heat exchanger.

9. The system of claim 1 , further comprising:
a flow line for recovering heated mixed refrigerant from the second heat exchanger; and
a third heat exchanger for cooling one or more additional streams via indirect heat exchange with the heated mixed refrigerant.

10. A system for the recovery of the olefins, the system comprising:
an absorber demethanizer for contacting a stream comprising methane, ethylene, and ethane with an absorbent and to recover an overheads vapor fraction comprising methane and ethylene and a bottoms fraction comprising the absorbent, ethylene, and ethane;
one or more extractive distillation and/or distillation stages for separating the bottoms fraction to recover an ethylene fraction and an ethane fraction;
a first heat exchanger for cooling and partially condensing the overheads vapor fraction to a temperature of about −40° C. or greater;
a second heat exchanger for cooling and partially condensing at least a portion of the cooled and partially condensed overhead vapor fraction via indirect heat exchange with a mixed refrigerant to a temperature of less than about −40° C.;
a separator for separating non-condensed vapors from the liquids condensed in the first and second heat exchangers to form an overhead liquid fraction and a methane fraction;
a flow line for feeding the overhead liquid fraction to the absorber demethanizer as a reflux;
a flow line, vessel, or mixing chamber for combining at least a portion of the methane and ethane fractions to form the mixed refrigerant.

11. The system of claim 10 , further comprising a heat exchanger for cooling the methanol-to-olefins reactor effluent upstream of the absorber demethanizer.

12. The system of claim 10 , further comprising:
a feed drum for splitting the methanol-to-olefins reactor effluent into a feed vapor stream and a feed liquid stream;
a flow line for supplying the feed vapor stream to an upper portion of the absorber demethanizer; and
a flow line for supplying the feed liquid stream to a lower portion of the absorber demethanizer.

13. The system of claim 10 , further comprising a side draw, a heat exchanger, and a return line for withdrawing a stream from the absorber demethanizer, cooling the stream, and returning the stream to the absorber demethanizer.

14. The system of claim 10 , further comprising:
a flow line for recovering heated mixed refrigerant from the second heat exchanger; and
a third heat exchanger for cooling one or more additional streams via indirect heat exchange with the heated mixed refrigerant.

15. A system for recovery of the olefins from a methanol to olefins reactor effluent, the system comprising:
an absorber demethanizer for contacting a stream comprising methane, ethylene, and ethane with an absorbent and to recover an overheads vapor fraction comprising methane and ethylene and a bottoms fraction comprising the absorbent, ethylene, and ethane;
a separation system for separating the bottoms fraction via one or more extractive distillation and/or distillation stages to recover an ethylene fraction and an ethane fraction;
a first heat exchanger for cooling and partially condensing the overheads vapor fraction to a temperature of about −40° C. or greater;
a separator for separating the cooled overheads vapor fraction to form a vapor fraction and a first overheads liquids fraction;
a second heat exchanger for cooling and partially condensing at least a portion of the vapor fraction, via indirect heat exchange with a mixed refrigerant, to a temperature of less than about −40° C.;
a separator for separating the vapor fraction to form a methane fraction and a second overheads liquids fraction;
a flow line for feeding at least a portion of the first and second overheads liquid fractions to the absorber demethanizer as a reflux;
a flow line, vessel, or mixing chamber for combining at least a portion of the methane and ethane fractions to form the mixed refrigerant.

16. The system of claim 15 , wherein the second heat exchanger and the separator for separating the vapor fraction are integral.

17. The system of claim 15 , further comprising:
a flow line for recovering heated mixed refrigerant from the second heat exchanger; and
a third heat exchanger for cooling one or more additional streams via indirect heat exchange with the heated mixed refrigerant.

18. The system of claim 15 , wherein the separation system for separating the bottoms fraction comprises one or more of a deethanizer, a depropanizer, or a deethylenize.

19. The system of claim 18 , further comprising a flow line for recovering propane from the depropanizer and for feeding the recovered propane, or a portion thereof, to the absorber demethaniz

Assignees

• Lummus Technology Inc

Inventors

• Kuzma Jr Peter Daniel
• De Haan Stephen
• Baumbach Daniel Lee

Classifications

• F25J2270/88

  Quasi-closed internal refrigeration or heat pump cycle, if not otherwise provided · CPC title

• F25J2200/80

  using integrated mass and heat exchange, i.e. non-adiabatic rectification in a reflux exchanger or dephlegmator · CPC title

• B01D53/1487

  Removing organic compounds · CPC title

• B01D3/40

  Extractive distillation · CPC title

• F25J3/0219

  Refinery gas, cracking gas, coke oven gas, gaseous mixtures containing aliphatic unsaturated CnHm or gaseous mixtures of undefined nature · CPC title