CO2 recovery unit and CO2 recovery method

Patent metadata

Field	Value
Publication number	US-12403422-B2
Application number	US-202117915804-A
Country	US
Kind code	B2
Filing date	Jan 13, 2021
Priority date	Apr 2, 2020
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

A CO 2 recovery unit includes a CO 2 absorber that brings a gas having a low CO 2 concentration into countercurrent contact with a CO 2 absorbent to remove CO 2 from the gas. The CO 2 recovery unit further includes a first absorbent circulation line that supplies a CO 2 absorbent from a first CO 2 absorption section as a first circulation solution to an upper side of a first CO 2 absorption section; a second absorbent circulation line that supplies a CO 2 absorbent from a second CO 2 absorption section as a second circulation solution to an upper side of a second CO 2 absorption section; and an absorbent discharge line that discharges a part of the first circulation solution from the first absorbent circulation line and supply the part of the first circulation solution as a discharged solution to the second absorbent circulation section.

First claim

The invention claimed is:

1. A CO 2 recovery unit comprising:
a CO 2 absorber that brings a gas having a low CO 2 concentration into countercurrent contact with a CO 2 absorbent to remove CO 2 from the gas;
an absorbent regenerator that performs a heat exchange between a rich solution containing absorbed CO 2 and water vapor flowed from a reboiler to regenerate the CO 2 absorbent;
a rich solution supply line that discharges a rich solution in which CO 2 has been absorbed by the CO 2 absorbent in the CO 2 absorber, from a bottom part of the CO 2 absorber and supplies the rich solution to an upper side of the absorbent regenerator; and
a lean solution supply line that discharges a lean solution in which CO 2 has been released from the rich solution in the absorbent regenerator, from a bottom part of the absorbent regenerator and supplies the lean solution as the CO 2 absorbent to an upper side of the CO 2 absorber,
wherein the CO 2 absorber includes at least two or more CO 2 absorption sections including a first CO 2 absorption section and a second CO 2 absorption section located below the first CO 2 absorption section, and
the CO 2 recovery unit further comprises:
a first absorbent circulation line that discharges the CO 2 absorbent from the first CO 2 absorption section and supplies the CO 2 absorbent as a first circulation solution to an upper side of the first CO 2 absorption section;
a second absorbent circulation line that discharges the CO 2 absorbent from the second CO 2 absorption section and supplies the CO 2 absorbent as a second circulation solution to an upper side of the second CO 2 absorption section; and
an absorbent discharge line that discharges a part of the first circulation solution from the first absorbent circulation line and supply the part of the first circulation solution as a discharged solution to the second absorbent circulation line.

2. The CO 2 recovery unit according to claim 1 , wherein the gas has a CO 2 concentration of 10% by volume or less.

3. The CO 2 recovery unit according to claim 1 , wherein a separation ratio of flow rates of the first circulation solution to the discharged solution is set to 1:1 to 60:1.

4. The CO 2 recovery unit according to claim 1 , further comprising a water wash section on a downstream side of a gas flow in the first CO 2 absorption section.

5. The CO 2 recovery unit according to claim 1 , wherein the first absorbent circulation line includes a cooling part.

6. A CO 2 recovery method comprising:
a CO 2 absorption step of bringing a gas having a low CO 2 concentration into countercurrent contact with a CO 2 absorbent to remove CO 2 from the gas;
an absorbent regeneration step of performing a heat exchange between water vapor and a rich solution containing absorbed CO 2 to regenerate the CO 2 absorbent; and
a step of discharging a rich solution in which CO 2 has been absorbed at the CO 2 absorption step, supplying the rich solution to the absorbent regeneration step, discharging a lean solution in which CO 2 has been released from the rich solution at the absorbent regeneration step, and supplying the lean solution as the CO 2 absorbent to the CO 2 absorption step to recover CO 2 in the gas,
wherein the CO 2 absorption step includes at least two or more CO 2 absorption steps including a first CO 2 absorption step and a second CO 2 absorption step following the first CO 2 absorption step,
the CO 2 recovery method further comprises:
a first absorbent circulation step of discharging the CO 2 absorbent obtained at the first CO 2 absorption step and supplying the CO 2 absorbent as a first circulation solution to the first CO 2 absorption step;
a second absorbent circulation step of discharging the CO 2 absorbent obtained at the second CO 2 absorption step and supplying the CO 2 absorbent as a second circulation solution to the second CO 2 absorption step; and
an absorbent discharge step of discharging a part of the first circulation solution obtained at the first absorbent circulation step and supplying the part of the first circulation solution as a discharged solution to the second absorbent circulation step.

Assignees

• Mitsubishi Heavy Ind Ltd
• Kansai Electric Power Co

Inventors

• Tanaka Hiroshi
• Hirata Takuya
• Tsujiuchi Tatsuya
• Kamijo Takashi
• Kawasaki Shimpei

Classifications

• B01D2257/504

  Carbon dioxide · CPC title

• B01D2252/20478

  Alkanolamines · CPC title

• B01D53/78

  with gas-liquid contact · CPC title

• B01D53/62

  Carbon oxides · CPC title

• B01D53/18

  Absorbing units; Liquid distributors therefor (B01D3/16, B01D3/26, B01D3/30 take precedence; packing elements B01J19/30, B01J19/32) · CPC title