KR101422671B1 - Phase separation absorbent composition for removing acid gas and removing method of acid gas - Google Patents

Abstract

The present invention relates to a phase separating absorbent composition for removing an acidic gas and a method for removing acidic gas using the same, and more particularly, to an absorbent for removing only acidic gas in a gaseous effluent, A liquid phase of the portion where the acidic gas component is concentrated and a portion of the liquid phase which are not concentrated are separated from each other, and a method for removing acidic gas using the same. When the acid gas is removed by using the phase separation absorbent composition, energy can be drastically reduced as compared with the conventional acid gas removal process.

Description

[0001] The present invention relates to a phase separation absorbent composition for removing an acidic gas and a method for removing acid gas using the same.

The present invention relates to an absorbent for removing an acid component gas such as a flue gas, a petrochemical process gas, for example, CO ₂ , H ₂ S, COS and CS ₂ by an absorption method, And a method of removing acidic gas using the same. The present invention relates to a method for removing acidic gas using the same, and a method for removing acidic gas using the same. The problem of operation cost due to excessive energy consumption during regeneration, which is the greatest problem in the absorption process for eliminating carbon dioxide, can be drastically reduced.

Until now, the absorption method using alkanolamine has been commercialized in order to remove the acid component gas from the combustion gas and the petrochemical process gas, and many processes have actually been applied.

Typical methods include primary to tertiary alkanolamines such as mono ethanol amine (MEA), diethanolamine (DEA), methyl diethanol amine (MDEA) And many commercialization processes are applied. Especially, MEA process has a high absorption rate and a very low cost compared with other alkanolamines. However, when the absorption liquid is regenerated in the regeneration tower to absorb the acid gas and reuse the absorption liquid, There is a problem that is consuming a lot.

In order to remedy this problem, a secondary or tertiary amine has been used but some effects have been observed in terms of energy consumption, but no significant effect has been observed. The greatest part of the energy consumption occupies a large part of the reaction heat depending on the amine characteristics, and the latent heat of evaporation and the increase in the heat capacity due to the water mixed to prepare the absorption liquid are also very large.

Therefore, in order to overcome the above problems, some researchers have been developing a phase separation sorbent in which acid gas is absorbed and then reacted with the acid gas and the unreacted portion is separated into layers. Typical techniques include Renaud Cadours, Pierre- U.S. Published Patent Application No. 2006-0104877 and U.S. Published Patent Application No. 2007-0264180 filed by Louis Carrette et al.

U.S. Published Patent Application No. 2006-0104877 discloses a process for the production of N, N, N ', N', N "-pentamethyldiethylenetriamine by mixing with water and reacting with acid gas to absorb the acid gas and then separating into two liquid phases In order to separate the liquid phase, in the embodiment of the patent, 20% by weight of water and 80% by weight of reagent are used, and the proportion of the reagent is much higher than that of water to absorb the acid gas and then phase separation. The amount of water to be added is so small that the acid gas absorption ability is very low.

U.S. Patent Publication No. 2007-0264180 proposes a method of adding sulfuric acid, phosphoric acid, and the like to lower the pH in order to further facilitate the above-mentioned reagents. In this method, too, the phase separation rate is delayed only with the above reagent, so that the ratio of N, N, N ', N', N "-pentamethyldiethylenetriamine does not become lower than water, The same constraint as the arc is bound to follow.

In addition, Liang Hu et al. In US Pat. No. 7,846,407 disclose that when using alkanolamine as the absorption liquid, fatty alcohol having C 8 -C 12 carbon atoms is mixed with water instead of water and reacted with acid gas It was suggested that the part which did not react with the alkanolamine reacted with the acid gas was separated into the liquid phase. However, the patent does not take into account the corrosiveness of alkanolamines. For example, it is not possible to use more than 30% by weight of MEA as a highly corrosive compound, and the concentration of alkanolamine absorbing acid gas is almost pure amine. It is difficult to use them practically, and when the aliphatic alcohol having a long side chain is used as a solvent, there is a restriction on its use due to problems such as viscosity increase.

In addition, International Patent Publication No. 2010-044836 discloses a technique having an emulsion concept. In the patent, water is added. Since water is not mutually soluble with the fatty acid alcohol, it is emulsified and the amine contained in the aliphatic alcohol And then reacted with the acid gas to separate and dissolve the component in water. However, this method can be very complicated, and there is a problem in that it is necessary to devise a method in which the emulsified solution smoothly contacts the gas smoothly in the absorption tower.

In addition, Agar et al. Of Dormund University, Germany, have proposed a new method of using alkylamines without alcoholic groups without using alkanolamines in International Patent Publication No. 2008-015217. The alkylamines do not dissolve in water because they do not have an -OH group. The method disclosed in WO 2008-015217 is contrary to the above-mentioned methods. Since the alkylamine is not dissolved in water before reacting with the acid gas, it is present in two liquid phases. After the reaction with the acid gas, the alkylamine And the acidic components are combined with each other to become hydrophilic and thus become a single phase. Advantages of this method are that the regeneration temperature can be lowered to 100 ° C or less, which is lower than the temperature required for the alkanolamine to be about 120 ° C or more, thereby lowering the running cost. However, Since the phases are separated before being injected into the upper part of the tower, a method for uniformly mixing them is required. Also, a new additive or device capable of maintaining a uniformly dispersed alkylamine for a predetermined time should be proposed. I can not.

The present invention relates to a process for removing an acidic component gas such as CO ₂ , H ₂ S, COS, and CS ₂ contained in a gas such as combustion exhaust gas, petrochemical process gas, flue gas of a cement factory, blast furnace gas of a steel industry, In order to save the energy consumed when regenerating the absorption liquid using alkanolamine, the acid gas-dissolving part and the non-dissolved part are separated into two phases after the absorption process and only the part containing acid gas is regenerated, The present invention provides an energy-saving type phase-separation absorbent composition which can be remarkably reduced compared to a process and an acid gas removing method using the same.

In order to achieve the above object, the present invention relates to a process for the preparation of a pharmaceutical composition comprising 10 to 40% by weight of 2-diethylaminoethanol (diethylethanolamine; DEEA), 10 to 40% by weight of alkylamines and 20 to 50% A phase separation absorbent composition for acid gas removal is provided.

The alkyl amines may be selected from the group consisting of N, N, N ', N'-tetramethyl-1,3-propanediamine, N, N, N', N ', N "-pentamethyldiethylenetriamine, Amines, and dimethylcyclohexylamines. ≪ / RTI >

The acid gas may be any one or a combination of two or more selected from the group consisting of CO ₂ , H ₂ S, COS, and CS ₂ .

The present invention also relates to a process for preparing a phase separating absorbent comprising 10 to 40% by weight of 2-diethylaminoethanol (diethylethanolamine; DEEA), 10 to 40% by weight of alkylamines and 20 to 50% step; Absorbing a gaseous effluent containing an acidic gas into the phase separating absorbent; And a step of desorbing the acidic gas by treating nitrogen in the absorption liquid separated into two phases after the absorption.

According to the present invention, after the liquid absorbent prepared by mixing DEEA, alkyl amines and water reacts with the acid gas, the liquid phase is separated into the two portions of the portion containing the acidic gas and the portion not containing the acidic gas, It is possible to regenerate only the absorption liquid of the lower layer portion contained therein, and thus the regeneration energy can be remarkably reduced as compared with the general absorption liquid.

1 is a view showing a phase-separated absorption liquid absorbing an acidic gas according to an embodiment of the present invention,
FIG. 2 shows a state where the phase-separated absorption liquid of FIG. 1 is desorbed by absorption of CO ₂ at 80 ° C. using nitrogen and changed into a single phase.

Hereinafter, the present invention will be described in more detail.

The present invention relates to an absorbent for removing an acidic gas, which comprises mixing a specific activating agent and an alkylamine to absorb an acidic gas and then phase-separating the absorbed acid gas, or adding an alkylamine and a specific activating agent, The alkylamines which are not soluble in water dissolve in water because they are mixed, and after acid gas reaction, they are divided into acid gas absorbing part and non absorbing part so that only acid gas absorbing part is regenerated. Thus, acid gas And an acid gas removing process using the same.

More specifically, as a specific compound which can facilitate phase separation, 2-diethylaminoethanol (diethylethanolamine; DEEA) is mixed with water, alkyl amines are mixed to prepare a phase separating absorbent, When reacted with an acid gas, the absorption liquid is phase separated into two phases.

The alkylamines used herein may be all kinds of alkylamines, but some alkylamines are not regenerated because they react with acid gases and form solid salts. However, this kind of alkylamines can be avoided if the mixing ratio is limited to 1 mole or less.

Representative alkylamines which are well-phase-separated by mixing with DEEA are N, N, N ', N'-tetramethyl-1,3-propanediamine, dimethylcyclohexylamine, N, N, N' Triethylamine, tripropylamine, and the like. Particularly, triethylamine, tripropylamine, dimethylcyclohexylamine and the like which are not solely dissolved in water can be mixed with DEEA Before being dissolved and contacting with acid gas, it exists as a single liquid phase, that is, as a water-soluble absorbent, and after absorbing the acid gas, it is separated into two liquid phases as concentrated and unconcentrated portions of the acid gas.

Alkylamines include N, N, N ', N'-tetramethyl-1,3-propanediamine and N, N, N', N ', N "-pentamethyldiethylenetriamine, As described above, N, N, N ', N', N '' - pentamethyldiethylenetriamine is effective in the case of a very small amount of water in order to achieve phase separation. In order to promote phase separation, To adjust the pH. However, in the present invention, the addition of alkyl amines to DEEA / water facilitates the phase separation phenomenon.

In the present invention, the amount of water should be limited to 50% by weight or less, and if it exceeds this amount, phase separation may not occur. And the addition of DEEA is 10 to 40% by weight, and the other is formed of alkylamines. At this time, when the content of DEEA is less than 10% by weight or exceeds 40% by weight, phase separation may not occur.

When DEEA is used as an acid gas absorbent as in the present invention, most of the alkyl amines are mixed with water and can act as an activator of the phase separating absorbent if the content ratio is appropriate. In the present invention, in order to solve such a problem, only the portion absorbing the acid gas is regenerated, so that the portion of the absorbent to be regenerated as a whole is reduced Also, since the amount of water used is small, renewable energy can be greatly reduced.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the present invention is not limited by these examples.

≪ Example 1 >

DEEA, water and N, N, N ', N'-tetramethyl-1,3-propanediamine were mixed at 18 wt%, 42 wt% and 40 wt%, respectively. A mixed gas containing a CO ₂ concentration of 20% was absorbed into the prepared absorbent composition at 40 캜.

As a result, the single phase liquid sorbent was separated into two liquid phases while absorbing CO ₂ . After the absorption, the absorption liquid separated into two phases was changed to single phase by desorbing CO ₂ absorbed by nitrogen at 80 ° C.

The dissolved CO ₂ concentration in the upper layer was 0.066 mol CO ₂ / Liter and the lower CO ₂ concentration was 3.425 mol CO ₂ / Liter.

FIG. 1 shows an absorption liquid phase-separated after absorbing an acidic gas. FIG. 2 shows a state in which the absorption liquid is further changed into a single phase after regeneration at 80.degree.

≪ Example 2 >

DEEA, water, N, N, N ', N'-tetramethyl-1,3-propanediamine were mixed at 20 wt%, 45 wt% and 35 wt%, respectively. A mixed gas containing a CO ₂ concentration of 20% was absorbed into the prepared absorbent composition at 40 캜.

As a result, the single phase liquid sorbent was separated into two liquid phases while absorbing CO ₂ . After the absorption, the absorption liquid separated into two phases was changed to single phase by desorbing CO ₂ absorbed by nitrogen at 80 ° C.

When the two phases were completely adsorbed, the CO ₂ dissolved in the liquid phase of the upper layer was measured to be 0.086 mol CO ₂ / Liter and the CO ₂ concentration in the lower layer was found to be 3.76 mol CO ₂ / Liter.

≪ Comparative Example 1 &

DEEA, water, N, N, N ', N'-tetramethyl-1,3-propanediamine were mixed at 15 wt%, 51 wt% and 34 wt%, respectively. A mixed gas containing a CO ₂ concentration of 20% was absorbed into the prepared absorbent composition at 40 캜.

As a result, a lot of bubbles were generated during the absorption process, and the phase did not separate after the absorption,

≪ Example 3 >

DEEA, water, N, N, N ', N', N '' - pentamethyldiethylenetriamine were mixed at 27 wt%, 40 wt% and 33 wt%, respectively. A mixed gas containing a CO ₂ concentration of 20% was absorbed into the prepared absorbent composition at 40 캜.

As a result, the single phase liquid sorbent was separated into two liquid phases while absorbing CO ₂ . After the absorption, the absorption liquid separated into two phases was changed to single phase by desorbing CO ₂ absorbed by nitrogen at 80 ° C.

As a result of measuring the CO ₂ dissolved in the upper liquid phase in the presence of two phases is complete absorption 0.0597 mol CO ₂ / Liter, CO ₂ concentration of the lower layer is found to be 2.719 mol CO ₂ / Liter.

<Example 4>

DEEA, water, N, N, N ', N', N '' - pentamethyldiethylenetriamine were mixed at 15 wt%, 40 wt% and 45 wt%, respectively. A mixed gas containing a CO ₂ concentration of 20% was absorbed into the prepared absorbent composition at 40 캜.

As a result, the single phase liquid sorbent was separated into two liquid phases while absorbing CO ₂ . After the absorption, the absorption liquid separated into two phases was changed to single phase by desorbing CO ₂ absorbed by nitrogen at 80 ° C.

The CO ₂ concentration in the upper liquid phase was 0.156 mol CO ₂ / Liter and the lower CO ₂ concentration was 2.01 mol CO ₂ / Liter.

&Lt; Example 5 >

DEEA, water and triethylamine were mixed at 20 wt%, 40 wt% and 40 wt%, respectively, to prepare a liquid absorbent. A mixed gas containing a CO ₂ concentration of 20% was absorbed into the prepared absorbent composition at 40 캜.

As a result, the single phase liquid sorbent was separated into two liquid phases while absorbing CO ₂ . After the absorption, the absorption liquid separated into two phases was changed to single phase by desorbing CO ₂ absorbed by nitrogen at 80 ° C.

The dissolved CO ₂ concentration in the liquid phase of the upper layer was 0.176 mol CO ₂ / Liter and the lower CO ₂ concentration was 3.275 mol CO ₂ / Liter.

&Lt; Example 6 >

DEEA, water, and dimethylcyclohexylamine were mixed at 30 wt%, 40 wt%, and 30 wt%, respectively, to prepare a liquid absorbent. A mixed gas containing a CO ₂ concentration of 20% was absorbed into the prepared absorbent composition at 40 캜.

As a result, the single phase liquid sorbent was separated into two liquid phases while absorbing CO ₂ . After the absorption, the absorption liquid separated into two phases was changed to single phase by desorbing CO ₂ absorbed by nitrogen at 80 ° C.

As a result of measuring the CO ₂ dissolved in the upper liquid phase in the presence of two phases is complete absorption 0.198 mol CO ₂ / Liter, CO ₂ concentration of the lower layer is found to be 3.075 mol CO ₂ / Liter.

While the present invention has been particularly shown and described with reference to specific embodiments thereof, those skilled in the art will appreciate that such specific embodiments are merely preferred embodiments and that the scope of the present invention is not limited thereby. something to do. It is therefore intended that the scope of the invention be defined by the claims appended hereto and their equivalents.

Claims (4)

10 to 40% by weight of 2-diethylaminoethanol (diethylethanolamine; DEEA), 10 to 40% by weight of N, N, N ', N'-tetramethyl- % By weight of water. delete The composition according to claim 1, wherein the acid gas is any one or a combination of two or more selected from the group consisting of CO ₂ , H ₂ S, COS, and CS ₂ . 10 to 40% by weight of 2-diethylaminoethanol (diethylethanolamine; DEEA), 10 to 40% by weight of N, N, N ', N'-tetramethyl- Preparing a phase separating absorbent comprising water in weight percent;
Absorbing a gaseous effluent containing an acidic gas into the phase separating absorbent; And
Treating the absorption liquid separated into two phases after the absorption to desorb the acid gas
And removing the acidic gas.

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