EP-4741042-A1 - GAS TREATMENT APPARATUS AND GAS TREATMENT METHOD

EP4741042A1EP 4741042 A1EP4741042 A1EP 4741042A1EP-4741042-A1

Abstract

A gas treatment apparatus includes: an absorber that brings a gas to be treated containing an acidic compound and a treatment liquid into contact with each other for making the treatment liquid absorb the acidic compound contained in the gas to be treated, the treatment liquid being in a state where an amine and a second component are mixed with each other in a state before absorbing the acidic compound, and the treatment liquid phase-separating into a first phase portion mainly containing the amine and a second phase portion mainly containing the second component through absorption of the acidic compound; a regenerator that separates the acidic compound from the treatment liquid; and a treatment liquid recovery unit that brings the second phase portion, having flowed out of the absorber, into contact with a treatment liquid entraining gas in the absorber to recover the treatment liquid entrained in the treatment liquid entraining gas.

Inventors

MAEDA, NORIHIDE
KISHIMOTO, AKIRA
YOSHIZAWA, Mai
MACHIDA, HIROSHI
NORINAGA, Koyo

Assignees

KABUSHIKI KAISHA KOBE SEIKO SHO (KOBE STEEL, LTD.)
NATIONAL UNIVERSITY CORPORATION TOKAI NATIONAL HIGHER EDUCATION AND RESEARCH SYSTEM

Dates

Publication Date: 20260513
Application Date: 20240405

Claims (19)

A gas treatment apparatus comprising: an absorber that brings a gas to be treated containing an acidic compound that generates an acid through dissolution in water and a treatment liquid into contact with each other for making the treatment liquid absorb the acidic compound contained in the gas to be treated, the treatment liquid being in a state where an amine and a second component are mixed with each other in a state before absorbing the acidic compound, and the treatment liquid phase-separating into a first phase portion mainly containing the amine and a second phase portion mainly containing the second component through absorption of the acidic compound; a regenerator that heats the treatment liquid having absorbed the acidic compound to separate the acidic compound from the treatment liquid; and a treatment liquid recovery unit that brings at least one of the first phase portion and the second phase portion, both having flowed out of the absorber, into contact with a treatment liquid entraining gas to recover the treatment liquid entrained in the treatment liquid entraining gas, the treatment liquid entraining gas being either a gas in the absorber after the acidic compound is absorbed from the gas to be treated into the treatment liquid or a gas in the regenerator and containing the acidic compound.
The gas treatment apparatus according to claim 1, comprising a separator that separates the treatment liquid having absorbed the acidic compound into a treatment liquid mainly containing the first phase portion and a treatment liquid mainly containing the second phase portion.
The gas treatment apparatus according to claim 1, comprising a water washing unit that brings the treatment liquid entraining gas and washing water into contact with each other to recover the treatment liquid entrained in the treatment liquid entraining gas, wherein the treatment liquid recovery unit is disposed at a position where the treatment liquid phase-separated into the first phase portion and the second phase portion comes into contact with the treatment liquid entraining gas before coming into contact with the washing water in the water washing unit.
The gas treatment apparatus according to claim 1 or 2, comprising a separation promoting gas supply unit that supplies a separation promoting gas for promoting separation of the acidic compound from the treatment liquid to the regenerator, wherein the treatment liquid recovery unit is configured to bring at least one of the first phase portion and the second phase portion, both having flowed out of the absorber, into contact with the treatment liquid entraining gas.
The gas treatment apparatus according to claim 4, wherein the treatment liquid recovery unit is configured to bring at least one of the first phase portion and the second phase portion, both having flowed out of the absorber, into contact with a gas containing the acidic compound in the regenerator.
The gas treatment apparatus according to claim 4, wherein the separation promoting gas is a gas containing moisture or a gas composed of water vapor, and the gas treatment apparatus comprises a moisture removing unit that separates the moisture contained in the separation promoting gas from the separation promoting gas to be supplied to the regenerator.
The gas treatment apparatus according to claim 4, wherein the separation promoting gas is a gas containing moisture or a gas composed of water vapor, and the gas treatment apparatus comprises: a moisture removing unit that separates the moisture contained in the separation promoting gas from the separation promoting gas to be supplied to the regenerator; and a moisture supply path for supplying the moisture obtained in the moisture removing unit to at least one of: a water washing unit in the absorber; a water washing unit in the regenerator; a condenser provided on a supply path through which the acidic compound obtained in the regenerator is supplied to a supply destination; and a condenser provided on a discharge path through which a gas after treatment is discharged from the absorber.
A gas treatment apparatus comprising: an absorber that brings a gas to be treated containing an acidic compound that generates an acid through dissolution in water and a treatment liquid into contact with each other for making the treatment liquid absorb the acidic compound contained in the gas to be treated, the treatment liquid being in a state where an amine and a second component are mixed with each other in a state before absorbing the acidic compound, and the treatment liquid phase-separating into a first phase portion mainly containing the amine and a second phase portion mainly containing the second component through absorption of the acidic compound; a regenerator that heats the treatment liquid having absorbed the acidic compound to separate the acidic compound from the treatment liquid; a separation promoting gas supply unit that supplies a separation promoting gas that is a gas which promotes separation of the acidic compound from the treatment liquid and that is a gas containing moisture or is composed of water vapor to the regenerator; and a moisture removing unit that removes the moisture contained in the separation promoting gas from the separation promoting gas to be supplied to the regenerator.
A gas treatment method comprising: in an absorber, bringing a gas to be treated containing an acidic compound that generates an acid through dissolution in water and a treatment liquid into contact with each other to make the treatment liquid absorb the acidic compound contained in the gas to be treated, the treatment liquid being in a state where an amine and a second component are mixed with each other in a state before absorbing the acidic compound, and the treatment liquid phase-separating into a first phase portion mainly containing the amine and a second phase portion mainly containing the second component through absorption of the acidic compound; in a regenerator, heating the treatment liquid having absorbed the acidic compound to separate the acidic compound from the treatment liquid; causing the first phase portion and the second phase portion to flow out of the absorber; and bringing at least one of the first phase portion and the second phase portion, both having flowed out of the absorber, into contact with a treatment liquid entraining gas to recover the treatment liquid entrained in the treatment liquid entraining gas, the treatment liquid entraining gas being either a gas in the absorber after the acidic compound is absorbed from the gas to be treated into the treatment liquid or a gas in the regenerator and containing the acidic compound.
The gas treatment method according to claim 9, further comprising separating the treatment liquid having absorbed the acidic compound into a treatment liquid mainly containing the first phase portion and a treatment liquid mainly containing the second phase portion by a separator.
The gas treatment method according to claim 9 or 10, wherein the recovering the treatment liquid includes bringing an absorption liquid phase-separated into the first phase portion and the second phase portion into contact with the treatment liquid entraining gas, and the gas treatment method further comprises: thereafter bringing the gas in the absorber or the gas in the regenerator into contact with washing water to recover a treatment liquid entrained in the gas to be treated.
The gas treatment method according to claim 9 or 10, further comprising supplying, to the regenerator, a separation promoting gas that promotes separation of the acidic compound from the treatment liquid, wherein the recovery of the treatment liquid includes bringing at least one of the first phase portion and the second phase portion, both having flowed out of the absorber, into contact with the treatment liquid entraining gas.
The gas treatment method according to claim 12, wherein the recovery of the treatment liquid includes bringing at least one of the first phase portion and the second phase portion, both having flowed out of the absorber, into contact with a gas containing the acidic compound in the regenerator.
The gas treatment method according to claim 12, wherein the separation promoting gas is a gas containing moisture or a gas composed of water vapor, and the gas treatment method further comprises: separating moisture contained in the separation promoting gas from the separation promoting gas to be supplied to the regenerator; and bringing the separated moisture into contact with the treatment liquid entraining gas to recover the treatment liquid entrained in the treatment liquid entraining gas.
The gas treatment method according to claim 12, further comprising: separating moisture contained in the separation promoting gas from the separation promoting gas to be supplied to the regenerator; and supplying the separated moisture to at least one of a water washing unit in the absorber, a water washing unit in the regenerator, a condenser provided on a supply path through which an acidic compound obtained in the regenerator is supplied to a supply destination, and a condenser provided on a discharge path through which a gas to be treated after treatment is discharged from the absorber.
The gas treatment method according to claim 14, further comprising: measuring at least one of a concentration of a sulfur contained in the gas to be treated to be introduced into the absorber, a flow rate of the gas to be treated to be introduced into the absorber, a concentration of the amine or the second component contained in the gas after treatment discharged from the absorber, a concentration of the amine or the second component contained in the gas containing the acidic compound discharged from the regenerator, and a concentration of a degradation component contained in the treatment liquid to be introduced into the absorber; and adjusting at least one flow rate among a flow rate of moisture separated from the separation promoting gas and to be brought into contact with the treatment liquid entraining gas, a flow rate of the first phase portion or the second phase portion to be brought into contact with the treatment liquid entraining gas, and a flow rate of washing water to be supplied to a water washing unit provided in at least one of the absorber and the regenerator, on a basis of a result of the measurement.
The gas treatment method according to claim 16, wherein the adjusting the at least one flow rate includes: when a measurement result of at least one of a concentration of the amine or the second component contained in the gas after treatment discharged from the absorber and a concentration of the amine or the second component contained in the gas containing the acidic compound discharged from the regenerator becomes higher than a threshold value, increasing at least one of a flow rate of moisture separated from the separation promoting gas and to be brought into contact with the treatment liquid entraining gas and a flow rate of washing water to be supplied to the water washing unit; and when a measurement result of at least one of a concentration of the amine or the second component contained in the gas after treatment discharged from the absorber and a concentration of the amine or the second component contained in the gas containing the acidic compound discharged from the regenerator becomes lower than a threshold value, reducing at least one of a flow rate of moisture separated from the separation promoting gas and to be brought into contact with the treatment liquid entraining gas and a flow rate of washing water to be supplied to the water washing unit.
The gas treatment method according to claim 12, further comprising: measuring at least one of a concentration of a sulfur contained in the gas to be treated to be introduced into the absorber, a flow rate of the gas to be treated to be introduced into the absorber, a concentration of the amine or the second component contained in the gas after treatment discharged from the absorber, a concentration of the amine or the second component contained in the gas containing the acidic compound discharged from the regenerator, and a concentration of a degradation component contained in the treatment liquid to be introduced into the absorber; and adjusting at least one flow rate of a flow rate of moisture separated from the separation promoting gas and to be brought into contact with the treatment liquid entraining gas and a flow rate of the first phase portion or the second phase portion to be brought into contact with the treatment liquid entraining gas, on a basis of a result of the measurement.
A gas treatment method comprising: in an absorber, bringing a gas to be treated containing an acidic compound that generates an acid through dissolution in water and a treatment liquid into contact with each other to make the treatment liquid absorb the acidic compound contained in the gas to be treated, the treatment liquid phase-separating into a first phase portion mainly containing an amine phase and a second phase portion mainly containing a component phase other than an amine through absorption of the acidic compound; in a regenerator, heating the treatment liquid having absorbed the acidic compound to separate the acidic compound from the treatment liquid; removing moisture contained in a separation promoting gas from the separation promoting gas that promotes separation of the acidic compound from the treatment liquid; and supplying the separation promoting gas from which the moisture has been removed to the regenerator.

Description

Technical Field The present invention relates to a gas treatment apparatus and a gas treatment method. Background Art In recent years, carbon dioxide is considered to have a large influence on global warming. As an effective measure against this global warming problem, a technique of recovering CO2 from a large volume gas (CO2-containing gas) containing carbon dioxide (CO2) has attracted attention. Methods for recovering CO2 include various methods, and examples thereof include a chemical absorption method such as an amine absorption method. In the chemical absorption method, an alkaline aqueous solution such as an aqueous amine solution is used as a treatment liquid, and a CO2-containing gas is brought into contact with the treatment liquid, whereby the treatment liquid is made to absorb the acidic compound (CO2) in the gas. Then, the treatment liquid having absorbed the acidic compound is heated to release the acidic compound from the treatment liquid, and the acidic compound is recovered. A chemical absorption method using a treatment liquid containing an amine compound is disclosed in, for example, Patent Literature 1 cited below. In the gas treatment apparatus disclosed in Patent Literature 1, a treatment liquid containing an amine compound, an organic solvent, and water is used, and as the treatment liquid, a treatment liquid that absorbs an acidic compound and phase-separates into phases differing the content of the acidic compound is selected. The gas treatment apparatus disclosed in Patent Literature 1 is provided with a gas supply unit that supplies a separation promoting gas such as hydrogen gas to a regenerator. In this apparatus, since the separation promoting gas is supplied to the regenerator, energy required for separating and recovering the acidic compound is reduced. In such an amine absorption method using a treatment liquid containing an amine compound, it is known that the amine compound is entrained in the treated gas after the acidic compound is separated as disclosed in Patent Literature 2 cited below. To prevent the amine compound from being released outside the system together with the treated gas, the gas treatment apparatus disclosed in Patent Literature 2 is provided, in an absorber, with a water washing unit that brings the decarbonated exhaust gas from which CO2 has been removed into contact with washing water to remove a substance accompanying the decarbonated exhaust gas. When the amine compound is entrained in the treated gas, the amine compound may be entrained as vaporized gas or may be entrained as mist (liquid). When a water washing unit is provided in an absorber as in the gas treatment apparatus disclosed in Patent Literature 2, it is possible to prevent an amine compound from being discharged to the outside of the system, but since a treatment liquid comes into contact with washing water, there is a problem that the treatment liquid circulating between the absorber and a regenerator is diluted. On the other hand, when, for example, hydrogen gas is supplied to a regenerator as a separation promoting gas as in the gas treatment apparatus disclosed in Patent Literature 1, moisture close to saturation may be retained in the hydrogen gas when the hydrogen gas is obtained by water electrolysis. In this case, since the moisture retained in the hydrogen gas is supplied to the regenerator, there is a problem that the treatment liquid circulating between the absorber and the regenerator is diluted. When the treatment liquid circulating between the absorber and the regenerator is diluted as in the gas treatment apparatus disclosed in Patent Literature 1 or 2, the performance to separate the acidic compound by the treatment liquid may be deteriorated. Citation List Patent Literature Patent Literature 1: JP 6906766 B2Patent Literature 2: JP 5968159 B2 Summary of Invention An object of the present invention is to suppress dilution of a treatment liquid with water in a gas treatment apparatus or a gas treatment method for separating an acidic compound from a gas to be treated using a treatment liquid containing an amine. A gas treatment apparatus according to one aspect of the present invention includes: an absorber that brings a gas to be treated containing an acidic compound that generates an acid through dissolution in water and a treatment liquid into contact with each other for making the treatment liquid absorb the acidic compound contained in the gas to be treated, the treatment liquid being in a state where an amine and a second component are mixed with each other in a state before absorbing the acidic compound, and the treatment liquid phase-separating into a first phase portion mainly containing the amine and a second phase portion mainly containing the second component through absorption of the acidic compound; a regenerator that heats the treatment liquid having absorbed the acidic compound to separate the acidic compound from the treatment liquid; and a treatment liqui