KR20140100874A - Absorbent composition for removing acid gas components and removing method of acid components - Google Patents

Abstract

The present invention relates to an absorbent composition for removing acid gas components derived from gas and a method for removing the acid gas components using the same and, more specifically, to an absorbent for removing only acid gas among gaseous fumes. The absorbent maintains a single liquid phase before absorbing the acid gas, and is divided into an acid gas-concentrated portion and a non-concentrated liquid phase portion. According to another embodiment of the present invention, provided is an absorbent composition for removing sulfuric compounds. By using the absorbent composition for removing the acid gas to remove the acid gas, the energy consumption compared to an existing acid gas removal process can be remarkably reduced, and at the same time the energy consumption of the sulfuric compounds removal process can be drastically reduced.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an absorbent composition for removing an acidic gas component from a gas and a method for removing an acidic gas component using the same.

The present invention relates to an absorption method for removing acidic gas and sulfur compounds contained in natural gas, petroleum gas, synthesis gas, process gas, coal gasification gas and the like.

Gas produced in gas wells such as natural gas and gases generated in petrochemical processes contain acid gases such as CO ₂ and H ₂ S and also contain sulfur compounds such as COS, CS ₂ , Mercaptan .

Acid gas impurities, such as CO ₂ , H ₂ S, COS, CS _2, etc., are responsible for air pollution and must be removed from the final product. In addition, sulfur compounds such as COS, H ₂ S and mercaptans contained in gas are substances that must be removed before they are shipped to the final product because they are air pollutants. In petrochemical processes, etc., .

In general, for the removal of acid gas, physical absorption method, chemical absorption method, mixed absorption method in which physical absorption method and chemical absorption agent are mixed, and the like are commercialized and used.

Typical amines are monoethanolamine (MEA), diethanolamine (DEA), triethanolamine (TEA), methyldiethanolamine (hereinafter referred to as "MDEA"), ). These reagents are used to remove acidic gas and acidic gas by chemical reaction.

The physical absorption method is to remove the acidic gas component by dissolving the acidic gas component at a high pressure without chemical reaction, unlike the case where the chemical absorbent is bonded and removed by a chemical reaction. Typical physical absorbent is cyclotetramethylenesulfolane (hereinafter referred to as "Sulfolane N-methyl-2-pyrrolidone (NMP) and the like are used in many cases, and the mixed absorbent utilizes the merits of the chemical absorbent and the physical absorbent in combination.

The chemical absorbent can be used at normal pressure or high pressure, and the physical absorbent is used under high pressure.

However, the chemical absorbent of the acid gases CO _2, the removal of H ₂ S reacts very quickly high, but the removal efficiency for COS is the absorption rate CO ₂ And it is not easily removed in the absorption process.

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 used is too small and the acid gas absorption ability is very low.

In addition, Mercaptane (RSH) is a sulfur compound, but its chemical structure is RSH (R) (alkyl group), so it has fewer acidic properties than other sulfur compounds. Is difficult.

The removal of RSH can be better removed at higher pressures using a physical absorbent rather than a chemical absorbent, but due to the nature of the alkyl component, components of the hydrocarbon gas, such as methane, ethane, and propane, Problems may arise in the production of the final product and in the sulfur recovery process for the treatment of the recovered sulfur compounds.

Therefore, in order to remove the COS and RSH which are difficult to be removed by this absorption method, there are many processes using a method of removing the COS and RSH by installing an adsorption tower at the end of the absorption process. COS is obtained by hydrolysis A method of advancing the absorption process after conversion to H ₂ S that can easily react with the absorption liquid has been commercialized.

However, this method leads to an increase in cost due to the addition of equipment and operation, and in particular, in a process adopting a hydrolysis method for removing COS, heating is performed as a reaction condition for hydrolyzing the entire raw material gas There is a drawback that the energy consumption is large.

Therefore, in order to prevent the increase of complexity, investment cost and operating cost of such a process, many inventions relating to an absorbent and a process development capable of absorbing sulfuric compounds such as COS and RSH as well as acid gas of CO ₂ and H ₂ S have been proposed.

U.S. Patent No. 4336233 discloses a process for removing CO ₂ , H ₂ S and COS in a gas mixture comprising CO ₂ , H ₂ S or some COS, wherein methyl diethanolamine (hereinafter referred to as "MDEA" ) And piperazine were used in combination. The concentration of piperazine was used up to 0.8 mol / liter in aqueous solution, but the removal efficiency of RSH was not improved by this method.

US Pat. Nos. 4,997,730 and 6,337,059 also added piperazine to 1 mole of MDEA and added MDEA to a maximum of 6 mols, which greatly improved the absorption capacity for COS and H ₂ S, but did not improve the removal efficiency of RSH.

In U.S. Patent Publication No. 2010-0154637, it has been reported that the removal efficiency of RSH is improved compared to the conventional absorbent by mixing alkanolamine such as MDEA or DEA with thiodiglycol. However, The absorption of the group occurs at the same time, explaining that an acceptable level of alkyl absorption occurs.

However, the absorption efficiency of RSH of this absorbent was somewhat higher than that of the conventional absorbent, but the absorbing ability to remove the molecular sieve due to the removal of COS and RSH as described above was not observed. In order to remove this rear- The amount should be increased significantly.

U.S. Patent No. 8313718 proposed a method of removing H ₂ S and RSH by mixing chemical absorbents MDEA, MEA, DEA, TEA, DGA and the like, a group of physical absorbents Sulfolane et al. It was not big.

This patented method also removes acid gas components in the mixture gas or liquid, because physical absorbents have been used, so that a significant amount of hydrocarbons will be dissolved in the pressurization process, which can affect the treatment of the recovered sulfur compounds And loss of methane, ethane, and propane, which have added value in the product, may occur.

The present invention can remove sulfur compounds such as COS and RSH while removing acid gases such as CO ₂ , H ₂ S, COS and CS ₂ contained in the gas and the liquid. In addition, in the case of a mixed absorbent using a physical absorbent and a chemical absorber to remove the RSH, the absorption of the hydrocarbon component is solved, and methane, ethane An object of the present invention is to provide an acid gas absorbent composition in which the absorption rate of a sulfur compound is increased by using an aqueous solution of alkylamine, which is a chemical absorbent, to solve the problem of a physical absorbent for absorbing hydrocarbons of propane, and a method for removing acid gas using the acid gas absorbent composition. have.

In order to accomplish the above object, the present invention provides a process for the production of a composition comprising 5 to 40% by weight of diethylethanolamine (DEEA), 5 to 40% by weight of alkylamines, 20 to 70% by weight of water and 3 to 5% And a gas-derived acidic gas component-removing absorbent composition comprising the compound.

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 >

Wherein the piperazine compound is selected from the group consisting of piperazine, 2-methylpiperazine, 1,4-dimethylpiperazine, 1,4-diethylpiperazine, 2,3-dimethylpiperazine, 2,5-dimethylpiperazine, Dimethylpiperazine, 1,4-dipropylpiperazine, 1,4-diisopropylpiperazine, 1- (2-aminoethyl) piperazine, 2-aminoethylpiperazine, 1- (1-aminomethyl) piperazine, 1,4-bis (2-ethylhexyl) piperazine, 1- -Aminoethyl) piperazine, 1,4-bis (3-aminopropyl) piperazine, and piperazinol.

The acid gas may be CO ₂ , H ₂ S, COS, CS ₂ And mercaptans. [0035] The term " a "

The gas may be any one or a combination of two or more selected from the group consisting of natural gas, petroleum gas, synthesis gas, process gas and coal gasification gas.

The present invention also relates to a process for the production of a gas-containing composition comprising 5 to 40% by weight of diethylethanolamine (DEEA), 5 to 40% by weight of alkylamines, 20 to 70% by weight of water and 3 to 5% Preparing an absorbent for removing an acid gas component; Absorbing the exhaust gas containing the acidic gas into the phase separating absorbent.

Further, the method may further include the step of treating the absorbent for removing the gas-derived acid gas component after the absorption by treating nitrogen to desorb the acid gas.

INDUSTRIAL APPLICABILITY According to the present invention, an absorbent prepared by mixing DEEA, alkylamines, water and a piperazine-based compound can absorb only an acidic gas component derived from a gas and regenerate it, . In addition, when the absorbent reacts with the acid gas, the absorptivity to COS and mercaptan is much higher than that of the conventional absorbent, and the absorption rate of CO ₂ and H ₂ S is also kept high, so that the energy of the sulfur compound removing process can be remarkably reduced There is an effect such as reduction of operation cost and reduction of facility investment cost.

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.
3 is a flowchart illustrating a sulfur compound removing process according to an embodiment of the present invention,
4 is a graph showing absorption performance of COS for the absorbent for removing sulfur compounds shown in FIG. 3,
FIG. 5A is a graph showing absorption performance of COS for the absorbent for removing sulfur compounds shown in FIG. 3,
5B is a graph showing absorption performance of H ₂ S to the absorbent for removing sulfur compounds shown in FIG. 3,
FIG. 6 is a graph showing absorption performance of COS for the absorbent for removing sulfur compounds shown in FIG. 3,
7 is a graph showing absorption performance of RSH to the absorbent for removing sulfur compounds shown in Fig.

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

In order to easily separate an acidic gas component derived from a gas, 2-diethylaminoethanol (diethylethanolamine: DEEA) is selected as a specific activating agent, mixed with water, and then mixed with an alkylamine and a piperazine compound To prepare an absorbent for removing an acid gas component, wherein the piperazine compound may be previously dissolved in water and then mixed with other amines.

Although alkylamines of all kinds can be used as alkylamines, some alkylamines are not regenerated because they react with acid gas 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.

N, N, N ', N', N'-tetramethyl-1,3-propanediamine and N, N ', N'-pentamethyldiethylenetriamine in alkylamines are alkyl 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. In the present invention, however, the addition of alkylamines and a small amount of piperazine compound to DEEA and water makes it possible to easily achieve the phase separation.

The piperazine compound is selected from the group consisting of piperazine, 2-methylpiperazine, 1,4-dimethylpiperazine, 1,4-diethylpiperazine, 2,3-dimethylpiperazine, 2,5- (2-aminoethyl) piperazine, 2- aminoethylpiperazine, 1- (2-hydroxyethyl) piperazine, 1- Piperazines such as piperazine, 1- (1-hydroxylmethyl) piperazine, 1- (3-hydroxylpropyl) piperazine, 1,4- Aminoethyl) piperazine, 1,4-bis (3-aminopropyl) piperazine, and piperazine, and the piperazine-based compound can easily induce phase separation phenomenon Acts as an acid gas absorption promoter. The piperazine compound may be added separately, or it may be dissolved in water before mixing with amine.

The gas may be any one or a combination of two or more selected from the group consisting of natural gas, petroleum gas, synthesis gas, process gas and coal gasification gas.

In the present invention, the amount of DEEA is in the range of 5 to 40% by weight. If the amount of DEEA is outside the above range, smooth operation in the absorption tower may be restricted due to an increase in viscosity and the like.

The amount of the alkylamines is in the range of 10 to 40% by weight. If the amount of the alkylamines is out of the above range, smooth operation in the absorption tower can be restricted due to an increase in temperature, etc., and the cost is increased.

The amount of water is 20 to 70 wt%, and when the amount of water is 20 to 50 wt%, the acid gas component is absorbed in the absorbent composition. When the amount of the water is 51 wt% to 60 wt%, sulfur compounds such as COS and RSH are absorbed in the absorbent composition. If it exceeds the above range, absorption of acid gas may not occur. The amount of the piperazine compound is 3 to 5% by weight. Even if the amount of the piperazine compound is out of the above range, the gas-derived acidic gas component can be removed. However, if the amount exceeds the above range, the cost may increase.

In this case, by adding 3 to 5% by weight of the piperazine compound in the whole solution, it is possible to induce improvement of the absorption ratio of COS and RSH. Piperazine may be added separately or it may be dissolved in water before mixing with amine. However, it is not necessarily effective to mix DEEA, N, N, N ', N'-tetramethyl-1,3-propanediamine, and it is also effective to make an aqueous solution using each of them alone. Should remain the same.

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, N, N, N ', N'-tetramethyl-1,3-propanediamine and piperazine were mixed at 33 wt%, 34 wt%, 29 wt% and 4 wt%, respectively, Respectively. A mixed gas containing a CO ₂ concentration of 25% 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 measurement of CO ₂ dissolved in the liquid phase in the upper layer when it was present in two phases with absorption, 0.3 mol CO ₂ / Liter and CO ₂ The concentration was 3.1 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 and piperazine were mixed at 15 wt%, 40 wt%, 40 wt% and 5 wt%, respectively, Respectively. A mixed gas containing a CO ₂ concentration of 25% 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.

A result of the presence of two phases is complete absorption measure the CO ₂ dissolved in the liquid phase in the upper part 0.21 mol CO ₂ / Liter, CO ₂ concentration of the lower layer is found to be 3.07 mol CO ₂ / Liter.

≪ Example 3 >

DEEA, water, N, N, N ', N', N '' - pentamethyldiethylenetriamine and piperazine were mixed at 25 wt%, 40 wt%, 32 wt% and 3 wt% . A mixed gas containing a CO ₂ concentration of 25% 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.

A result of the presence of two phases is complete absorption measure the CO ₂ dissolved in the upper layer liquid and 0.07 mol CO ₂ / Liter, CO ₂ concentration of the lower layer is found to be 2.72 mol CO ₂ / Liter.

<Example 4>

DEEA, water, triethylamine, and 2-methylpiperazine were mixed at 20 wt%, 40 wt%, 36 wt%, and 4 wt%, respectively, to prepare a liquid absorbent. A mixed gas containing a CO ₂ concentration of 25% 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 liquid phase of the upper layer was 0.86 mol CO ₂ / Liter and the CO ₂ concentration in the lower layer was 2.75 mol CO ₂ / Liter.

&Lt; Example 5 >

DEEA, water, dimethylcyclohexylamine and 2-methylpiperazine were mixed at 26 wt%, 40 wt%, 30 wt% and 4 wt%, respectively, to prepare a liquid absorbent. A mixed gas containing a CO ₂ concentration of 25% 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 desorption of CO ₂ absorbed by nitrogen at 80 ° C.

The CO ₂ concentration in the upper liquid phase was 0.55 mol CO ₂ / Liter and the lower CO ₂ concentration was 2.7 mol CO ₂ / Liter.

&Lt; Example 6 >

DEEA, N, N, N ', N'-tetramethyl-1,3-propanediamine and water in amounts of 31 wt%, 14 wt% and 52 wt%, respectively, Respectively. 5% by volume of CO ₂ , 250 ppm of COS and 450 ppm of H ₂ S was absorbed into the prepared absorbent composition at 40 ° C at a flow rate of 500 ml / min.

In order to confirm the performance of the prepared absorbent, absorption experiments were carried out under the same conditions as the absorption liquids containing 50% by weight of MDEA and 50% by weight of water and 5% by weight of piperazine in a mixture thereof.

Referring to FIG. 4, aMDEA, which is known to be commercially available for the absorption of COS, shows a breakthrough concentration immediately after COS starts to be absorbed. However, the absorbent of the present invention begins to break down after about 70 minutes At the end of the reaction, the concentration of COS remained lower than that of aMDEA.

&Lt; Example 7 >

DEEA, N'-tetramethyl-1,3-propanediamine and water were mixed in amounts of 27 wt%, 7 wt% and 63 wt% and 3 wt% of piperazine, respectively, to prepare 60 cc of a liquid absorbent. A mixed gas of 5 vol% CO ₂ , 250 ppm COS and 450 ppm H ₂ S was absorbed into the prepared absorbent composition at 40 ° C at a flow rate of 500 ml / min.

In order to confirm the performance of the prepared absorbent, absorption experiments were carried out under the same conditions of an absorption liquid containing 50% by weight of MDEA and 50% by weight of water and 5% by weight of piperazine in a mixed solution thereof,

5A and 5B, aMDEA, which is known for commercial absorption of COS, shows that the concentration of COS is rapidly disrupted as COS starts to be absorbed. However, the absorbent composition for removing sulfur compounds of the present invention shows a COS is not released and shows complete absorption.

Analysis of not only COS but also H ₂ S showed that the absorbent of the present invention did not break down until the reaction was completed.

The absorbent for removing sulfur compounds showed not only COS but also excellent removal of H ₂ S.

&Lt; Example 8 >

DEEA, N'-tetramethyl-1,3-propanediamine and water were mixed in amounts of 33 wt%, 30 wt% and 33 wt%, respectively, and 4 wt% of piperazine to prepare 60 cc of a liquid absorbent. A mixed gas of 5 vol% CO ₂ , 250 ppm COS and 450 ppm H ₂ S was absorbed into the prepared absorbent composition at 40 ° C at a flow rate of 500 ml / min.

The performance of the prepared absorbent was confirmed. Referring to FIG. 6, the absorbent for removing sulfur compounds showed breakage after about 80 minutes from the start of absorption, showing excellent absorption of COS.

&Lt; Example 9 >

DEEA, N'-tetramethyl-1,3-propanediamine and water were mixed in amounts of 31 wt%, 14 wt% and 50 wt%, respectively, and 5 wt% of piperazine to prepare 60 cc of a liquid absorbent. A mixed gas of 5 vol% CO2, 250 ppm methylmercaptan and 450 ppm H ₂ S was absorbed into the prepared absorbent composition at 40 ° C at a flow rate of 500 ml / min.

HySweet absorbent, a commercial RSH absorbent, was prepared and compared for comparison with the prepared absorbent.

Referring to FIG. 7, it can be seen that the concentration of the absorbent prepared in Example 9 is high and low at the time when the breakthrough time is late and the reaction is terminated.

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 (7)

Removal of gaseous acidic gas components comprising 5 to 40% by weight of diethylethanolamine (DEEA), 5 to 40% by weight of alkylamines, 20 to 70% by weight of water and 3 to 5% by weight of piperazine- Absorbent composition. The method according to claim 1,
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, Amine, and dimethylcyclohexylamine. The absorbent composition for removing an acid gas component according to any one of claims 1 to 3, The method according to claim 1,
Wherein the piperazine compound is selected from the group consisting of piperazine, 2-methylpiperazine, 1,4-dimethylpiperazine, 1,4-diethylpiperazine, 2,3-dimethylpiperazine, 2,5-dimethylpiperazine, Dimethylpiperazine, 1,4-dipropylpiperazine, 1,4-diisopropylpiperazine, 1- (2-aminoethyl) piperazine, 2-aminoethylpiperazine, 1- (1-aminomethyl) piperazine, 1,4-bis (2-ethylhexyl) piperazine, 1- -Aminoethyl) piperazine, 1,4-bis (3-aminopropyl) piperazine, and piperazinol. The method according to claim 1,
The acid gas component may be CO ₂ , H ₂ S, COS, CS ₂ And mercaptans. 5. The absorbent composition according to any one of claims 1 to 4, The method according to claim 1,
Wherein the gas is any one or a combination of two or more selected from the group consisting of natural gas, petroleum gas, synthesis gas, process gas and coal gasification gas. Removal of gaseous acidic gas components comprising 5 to 40% by weight of diethylethanolamine (DEEA), 5 to 40% by weight of alkylamines, 20 to 70% by weight of water and 3 to 5% by weight of piperazine- Preparing an absorbent for absorption;
Absorbing an acidic gas-absorbing agent into the gas-derived acidic gas component absorbent. The method of claim 6,
Further comprising the step of desorbing the acidic gas by treating the absorbent for removing the gas-derived acidic gas component after the absorption by treating nitrogen.

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