US 7,740,688 B2Granted

Process and apparatus for carbon dioxide recovery

AssigneePraxair Technology, Inc.

InventorRavi Kumar

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Abstract

The present invention generally relates to vacuum pressure swing adsorption (VPSA) processes and apparatus to recover carbon dioxide having a purity of approximately ≧90 mole % from streams containing at least carbon dioxide and hydrogen (e.g., syngas). The feed to the CO2 VPSA unit can be at super ambient pressure. The CO2 VPSA unit produces three streams, a H2-enriched stream, a H2-depleted stream and a CO2 product stream. When the CO2 VPSA unit is installed between an SMR/shift reactor and a H2 PSA unit, hydrogen recovery is expected to be increased by extracting CO2, thereby increasing hydrogen partial pressure in the H2 PSA feed. The stream from the CO2 VPSA unit, normally used as fuel, is recycled as feed to increase CO2 recovery. The recovered CO2 can be further upgraded, sequestered or used in applications such as enhanced oil recovery (EOR).

Claims85

Dependent claims

A vacuum pressure swing adsorption (VPSA) process for the recovery of carbon dioxide from a feed stream, wherein the feed stream comprises a multi-component gas mixture comprising at least carbon dioxide and hydrogen, in a VPSA unit comprising at least one adsorption bed containing at least one CO2-selective adsorbent, the process comprising:

(a) feeding at least a portion of the feed stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(b) depressurizing the at least one adsorption bed in a first depressurization step from the first pressure to a second pressure within a second pressure range wherein the second pressure is lower than the first pressure in a same direction as or in a direction opposite to the feed flow;
(c) depressurizing the at least one adsorption bed in a second depressurization step from the second pressure to a third pressure within a third pressure range wherein the third pressure is lower than the second pressure and in a same direction as or in a direction opposite to the feed flow;
(d) depressurizing the at least one adsorption bed in a third depressurization step from the third pressure to a fourth pressure within a fourth pressure range wherein the fourth pressure is lower than the third pressure and close to ambient pressure, and in a same direction as the feed flow or in a direction opposite the feed flow to produce a CO2-rich stream, wherein a first portion of the CO2-rich stream is compressed and recycled into the feed stream and feeding the feed stream with said recycled first portion to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
and
(e) evacuating the at least one adsorption bed from the fourth pressure range to a pressure below ambient in a direction opposite to or in a same direction as the feed flow to produce CO2 product;
(f) feeding a second portion of the CO2-rich stream of step (d) to the at least one adsorption bed at a pressure below ambient to equalize the pressure in said bed;
(g) pressure equalizing the at least one adsorption bed in a second pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(h) further pressure equalizing the at least one adsorption bed in a third pressure equalization step in a direction opposite to or in a same direction as the feed flow;
and
(i) repressurizing the at least one adsorption bed in a repressurization step to the first pressure range;
wherein the process is repeated cyclically.

9 more elements

(a) feeding at least a portion of the feed stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(b) depressurizing the at least one adsorption bed in a first depressurization step from the first pressure to a second pressure within a second pressure range wherein the second pressure is lower than the first pressure in a same direction as or in a direction opposite to the feed flow;
(c) depressurizing the at least one adsorption bed in a second depressurization step from the second pressure to a third pressure within a third pressure range wherein the third pressure is lower than the second pressure and in a same direction as or in a direction opposite to the feed flow to produce a CO2-rich stream, wherein the CO2-rich stream is compressed and recycled into the feed stream, and feeding the feed stream with said recycled CO2-rich stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(d) depressurizing the at least one adsorption bed in a third depressurization step from the third pressure to a fourth pressure within a fourth pressure range wherein the fourth pressure is lower than the third pressure and in a same direction as or in a direction opposite to the feed flow;
(e) evacuating the at least one adsorption bed from the fourth pressure range to a pressure below ambient in a direction opposite to or in a same direction as the feed flow to produce CO2 product;
(f) feeding depressurized gas from step (d) to the at least one adsorption bed at a pressure below ambient to equalize the pressure in said bed;
(g) further pressure equalizing the at least one adsorption bed in a second pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(h) repressurizing the at least one adsorption bed in a repressurization step to the first pressure range;
wherein the process is repeated cyclically.

6 more elements

(a) feeding at least a portion of the feed stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(b) depressurizing the at least one adsorption bed in a first depressurization step from the first pressure to a second pressure within a second pressure range wherein the second pressure is lower than the first pressure in a same direction as or in a direction opposite to the feed flow;
(c) depressurizing the at least one adsorption bed in a second depressurization step from the second pressure to a third pressure within a third pressure range wherein the third pressure is lower than the second pressure and in a same direction as or in a direction opposite to the feed flow;
(d) depressurizing the at least one adsorption bed in a third depressurization step from the third pressure to a fourth pressure within a fourth pressure range wherein the fourth pressure is lower than the third pressure and in a same direction as or in a direction opposite to the feed flow to produce a CO2-rich stream, wherein the CO2-rich stream is compressed and recycled into the feed stream, and feeding the feed stream with said recycled CO2-rich stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(e) depressurizing the at least one adsorption bed in a fourth depressurization step from the fourth pressure to a fifth pressure within a fifth pressure range wherein the fifth pressure is lower than the fourth pressure and in a same direction as or in a direction opposite to the feed flow;
(f) evacuating the at least one adsorption bed from the fourth pressure range to a pressure below ambient in a direction opposite to or in a same direction as the feed flow to produce CO2product;
(g) feeding depressurized gas from step (e) to the at least one adsorption bed at a pressure below ambient to equalize the pressure in said bed;
(h) further pressure equalizing the at least one adsorption bed in a second pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(i) further pressure equalizing the at least one adsorption bed in a third pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(j) repressurizing the at least one adsorption bed in a repressurization step to the first pressure range;
wherein the process is repeated cyclically.

8 more elements

(a) feeding at least a portion of the feed stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(b) depressurizing the at least one adsorption bed in a first depressurization step from the first pressure to a second pressure within a second pressure range wherein the second pressure is lower than the first pressure in a same direction as or in a direction opposite to the feed flow;
(c) depressurizing the at least one adsorption bed in a second depressurization step from the second pressure to a third pressure within a third pressure range wherein the third pressure is lower than the second pressure and in a same direction as or in a direction opposite to the feed flow;
(d) depressurizing the at least one adsorption bed in a third depressurization step from the third pressure to a fourth pressure within a fourth pressure range wherein the fourth pressure is lower than the third pressure, and in a same direction as the feed flow or in a direction opposite the feed flow to produce a CO2-rich stream, wherein the CO2-rich stream is compressed and recycled into the feed stream and feeding the feed stream with said recycled first portion to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
and
(e) depressurizing the at least one adsorbent bed in a blowdown step from the fourth pressure to a fifth pressure within a fifth pressure range, wherein the fifth pressure is lower than the fourth pressure;
(f) evacuating the at least one adsorption bed from the fifth pressure range to a pressure below ambient in a direction opposite to or in a same direction as the feed flow to produce CO2 product;
(g) pressure equalizing the at least one adsorption bed in a first pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(h) further pressure equalizing the at least one adsorption bed in a second pressure equalization step in a direction opposite to or in a same direction as the feed flow;
and
(i) repressurizing the at least one adsorption bed in a repressurization step to the first pressure range;
wherein the process is repeated cyclically.

9 more elements

(a) feeding at least a portion of the feed stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(b) depressurizing the at least one adsorption bed in a first depressurization step from the first pressure to a second pressure within a second pressure range wherein the second pressure is lower than the first pressure in a same direction as or in a direction opposite to the feed flow;
(c) depressurizing the at least one adsorption bed in a second depressurization step from the second pressure to a third pressure within a third pressure range wherein the third pressure is lower than the second pressure and in a same direction as or in a direction opposite to the feed flow;
(d) depressurizing the at least one adsorption bed in a third depressurization step from the third pressure to a fourth pressure within a fourth pressure range wherein the fourth pressure is lower than the third pressure and in a same direction as or in a direction opposite to the feed flow;
(e) depressurizing the at least one adsorption bed in a fourth depressurization step from the fourth pressure to a fifth pressure within a fifth pressure range wherein the fifth pressure is lower than the fourth pressure and in a same direction as or in a direction opposite to the feed flow to produce a CO2-rich stream, wherein the CO2-rich stream is compressed and recycled into the feed stream, and feeding the feed stream with said recycled CO2-rich stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(f) depressurizing the at least one adsorbent bed in a blowdown step from the fifth pressure to a sixth pressure within a sixth pressure range, wherein the sixth pressure is lower than the fifth pressure;
(g) evacuating the at least one adsorption bed from the sixth pressure range to a pressure below ambient in a direction opposite to or in a same direction as the feed flow to produce CO2 product;
(h) pressure equalizing the at least one adsorption bed in a first pressure equalization step in a direction opposite to or in the same direction as the feed flow;
(i) further pressure equalizing the at least one adsorption bed in a second pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(j) further pressure equalizing the at least one adsorption bed in a third pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(k) repressurizing the at least one adsorption bed in a repressurization step to the first pressure range;
wherein the process is repeated cyclically.

9 more elements

(a) feeding at least a portion of the feed stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(b) depressurizing the at least one adsorption bed in a first depressurization step from the first pressure to a second pressure within a second pressure range wherein the second pressure is lower than the first pressure in a same direction as or in a direction opposite to the feed flow;
(c) depressurizing the at least one adsorption bed in a second depressurization step from the second pressure to a third pressure within a third pressure range wherein the third pressure is lower than the second pressure and in a same direction as or in a direction opposite to the feed flow;
(d) depressurizing the at least one adsorption bed in a third depressurization step from the third pressure to a fourth pressure within a fourth pressure range wherein the fourth pressure is lower than the third pressure and in a same direction as or in a direction opposite to the feed flow to produce a CO2-rich stream, wherein the CO2-rich stream is compressed and recycled into the feed stream, and feeding the feed stream with said recycled CO2-rich stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(e) evacuating the at least one adsorption bed from the fourth pressure range to a pressure below ambient in a direction opposite to or in a same direction as the feed flow to produce CO2 product;
(f) pressure equalizing the at least one adsorption bed in a first pressure equalization step in a direction opposite to or in the same direction as the feed flow;
(g) further pressure equalizing the at least one adsorption bed in a second pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(h) repressurizing the at least one adsorption bed in a repressurization step to the first pressure range;
wherein the process is repeated cyclically.

6 more elements

(a) feeding at least a portion of the feed stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(b) depressurizing the at least one adsorption bed in a first depressurization step from the first pressure to a second pressure within a second pressure range wherein the second pressure is lower than the first pressure in a same direction as or in a direction opposite to the feed flow;
(c) depressurizing the at least one adsorption bed in a second depressurization step from the second pressure to a third pressure within a third pressure range wherein the third pressure is lower than the second pressure and in a same direction as or in a direction opposite to the feed flow;
(d) depressurizing the at least one adsorption bed in a third depressurization step from the third pressure to a fourth pressure within a fourth pressure range wherein the fourth pressure is lower than the third pressure and in a same direction as or in a direction opposite to the feed flow;
(e) depressurizing the at least one adsorption bed in a fourth depressurization step from the fourth pressure to a fifth pressure within a fifth pressure range wherein the fifth pressure is lower than the fourth pressure and in a same direction as or in a direction opposite to the feed flow to produce a CO2-rich stream, wherein the CO2-rich stream is compressed and recycled into the feed stream, and feeding the feed stream with said recycled CO2-rich stream to the at least one adsorption bed at a first pressure within a first pressure range for a predetermined time to produce a hydrogen-enriched stream;
(f) evacuating the at least one adsorption bed from the fifth pressure range to a pressure below ambient in a direction opposite to or in a same direction as the feed flow to produce CO2product;
(g) pressure equalizing the at least one adsorption bed in a first pressure equalization step in a direction opposite to or in the same direction as the feed flow;
(h) further pressure equalizing the at least one adsorption bed in a second pressure equalization step in a direction opposite to or in a same direction as the feed flow;
(i) further pressure equalizing the at least one adsorption bed in a third pressure equalization step in a direction opposite to or in a same direction as the feed flow;
and
(j) repressurizing the at least one adsorption bed in a repressurization step to the first pressure range;
wherein the process is repeated cyclically.

9 more elements

Dependencies are inferred from the claim text.

Facts

Application: 11/527,015Filed 26 Sep 2006
Published: US 2008/0072752 A127 Mar 2008
Granted: 22 Jun 2010
Term ends: Not estimatedThe source records don’t support an estimate.

Classification33 codes

B01D 53/0476
Pressure swing adsorption: vacuum pressure swing adsorption
C01B 3/56
Separation of hydrogen or hydrogen-containing gases from gaseous mixtures, e.g. purification: by contacting with solids; Regeneration of used solids
B01D 2256/22
Main component in the product gas stream after treatment: carbon dioxide
B01D 2257/108
Single element gases other than halogens: hydrogen