KR101883878B1 - Apparatus and method for removing acidic gas containing natural gas - Google Patents

Abstract

The present invention relates to an apparatus and a method for removing acidic gas contained in a natural gas, comprising: a first absorption tower (101) for receiving natural gas and removing an acid gas contained in the natural gas with a first absorbent; A second absorption tower (102) for receiving natural gas treated in the first absorption tower to remove residual acid gas contained in the natural gas with a second absorbent; A regeneration tower (103) for regenerating the first absorbent discharged from the first absorption tower; An absorbent mixer (104) for mixing a second absorbent discharged from the second absorption tower with a semi-lean absorbent discharged from the middle of the regeneration tower; A first line (105) connecting the bottom of the first absorber and the middle of the regeneration tower to introduce a first absorbent discharged from the first absorber into the regeneration tower; A second line 106 connecting the lower part of the regeneration tower and the upper part of the second absorption tower to introduce the regenerated lean absorbent into the regeneration tower into the second absorption tower; A third line 107 connecting the middle of the regeneration tower to the sorbent mixer to introduce the regenerated semi-lean sorbent into the sorbent mixer; A fourth line (108) connecting the bottom of the second absorber to the absorber mixer to introduce a second absorbent discharged from the second absorber into the sorbent mixer; And a fifth line (109) connecting the absorbent mixer and the upper portion of the first absorption tower to introduce the mixed absorbent mixed in the absorbent mixer into the first absorption tower, whereby the acidic gas is introduced at a very low concentration, 50 ppm or less and hydrogen sulfide to 3 ppm or less, and the energy consumption can be reduced by about 15% or more as compared with the conventional one.

Description

[0001] The present invention relates to an apparatus and a method for removing acidic gas contained in natural gas,

The present invention relates to an apparatus and a method for removing acidic gas contained in natural gas, which can reduce the concentration of acidic gas in the natural gas to the ppm level and reduce the energy consumption by 15% or more as compared with the prior art.

Liquefied Natural Gas-Floating Production (LNGFPSO) moves to a remote marine gas field and floats in the ocean, producing, storing, and delivering LNG. Offloading the marine mobile multifunctional plant.

The plant is composed of a floating structure with pretreatment, liquefaction and storage facilities for the natural gas introduced from the submarine gas field. It is less costly to manufacture than the previous natural gas production method, It is movable.

The natural gas from the marine gas field is mainly composed of methane and other hydrocarbons such as ethane, propane and butane. The impurities include an acid gas component such as carbon dioxide (CO ₂ ) and hydrogen sulfide (H ₂ S) , Water (H ₂ O), mercury (Hg), and the like.

When the temperature of natural gas is low with natural gas, it may cause the problem of generating hydrate or ice and clogging of the plant equipment. Mercury may be caused by the brittleness of aluminum plate plate fin heat exchanger cause. In addition, CO ₂ and heavy gas components can cause CO ₂ freezing problems in a cryogenic plant, resulting in clogging.

Therefore, a pretreatment process is introduced before these impurities in the natural gas are sent to the liquefaction process, and these impurities must be removed to a certain level or less.

On the other hand, the marine pretreatment process occupies up to 50% of the available space of the LNG-FPSO deck depending on the impurity content of the raw material gas, which greatly affects the economical efficiency of the FPSO, which depends greatly on the space required. In addition, since the marine pretreatment process should be able to maintain operation stability and separation performance in rough marine environment and ship flow, a robust structure and deck design are essential.

Also, it is necessary to optimize the design to cope with the change of the natural gas composition of the marine gas field mined and the deterioration of the pretreatment process according to the hull motion.

As described above, the LNG pretreatment step includes an acidic gas removal device for removing carbon dioxide and hydrogen sulfide, which are acidic gas components contained in natural gas.

Amine absorption process is mainly used for such acid gas removal technology. Examples of the amine-based absorbent used in the amine absorption process include MEA (Monoethanol amine) and DEA (Diethanol amine). Currently, absorbents such as Piperazine and the like added to MDEA (Methyldiethanol amine) Licensor process) is mainly used. When carbon dioxide content is high, Piperazine is used as an additive in K ₂ CO ₃ aqueous solution which is improved by Benfield Process.

Since the process of using the chemical absorbent such as an amine-based absorbent is relatively less sensitive to partial pressure of carbon dioxide and hydrogen sulfide, the two components can be lowered to the ppm level, but the regeneration requires a large amount of renewable energy .

In addition, when the amine absorption process is applied to a floating structure such as LNG-FPSO, the area and height of the absorber must be designed to be sufficiently large in preparation for the flow of the structure. If the absorption tower is high, motion, the distribution of the fluid flowing through the absorption tower becomes uneven and the absorption of the acid gas is lowered.

Accordingly, there is a demand for an apparatus capable of reducing the acid gas to ppm level and reducing energy consumption while being less affected by ship-motion.

Korean Patent Publication No. 2015-0031769 Korea Patent No. 1190725 United States Patent No. 8,123,842

An object of the present invention is to provide an apparatus for removing acidic gas contained in natural gas, which can reduce energy consumption in a natural gas to a very low concentration while consuming less energy.

It is another object of the present invention to provide a method for removing acidic gas contained in natural gas.

In order to accomplish the above object, an apparatus for removing acidic gas contained in natural gas according to the present invention includes a first absorption tower for receiving natural gas through a lower portion thereof and removing an acidic gas contained in the natural gas with a first absorbent 101);

A second absorber (102) for receiving the natural gas discharged from the first absorber and discharged through the lower portion to remove residual acid gas contained in the natural gas with a second absorber;

A regeneration tower (103) for supplying and regenerating a first absorbent discharged through an upper portion of the first absorption tower through an intermediate portion;

An absorbent mixer (104) for mixing a second absorbent discharged through the lower part of the second absorption tower and a semi-lean absorbent discharged from the middle part of the regeneration tower;

A first line (105) connecting a lower portion of the first absorber and an intermediate portion of the regeneration tower to introduce a first absorbent discharged through a lower portion of the first absorber into the regeneration tower through an intermediate portion;

A second line (106) connecting the lower part of the regeneration tower and the upper part of the second absorption tower to introduce the lean absorbent regenerated in the regeneration tower and discharged through the lower part to the second absorption tower through the upper part;

A third line 107 connecting the intermediate portion of the regeneration tower and the absorbent mixer to introduce the semi-lean absorbent regenerated in the regeneration tower and discharged through the intermediate portion into the absorbent mixer;

A fourth line (108) connecting the lower portion of the second absorption tower and the absorbent mixer to introduce a second absorbent discharged through the lower portion of the second absorption tower into the absorbent mixer; And

And a fifth line 109 connecting the absorbent mixer and the upper portion of the first absorption tower to introduce the mixed absorbent mixed in the absorbent mixer into the first absorption tower through the upper portion.

And a flash drum 110 disposed in the first line 105 to remove a portion of methane and acid gas absorbed in the first absorbent.

A heat exchanger 111 disposed at a position where the first line 105 and the second line 106 intersect to perform heat exchange between the first absorbent flowing into the regeneration tower and the lean absorbent discharged from the regeneration tower, As shown in FIG.

And a reboiler 112 disposed in the second line 106 to evaporate a small amount of acid gas and water contained in the lean absorbent discharged from the regeneration tower.

A replenishing device 113 disposed in the second line 106 for replenishing moisture lost during the process to the lean absorbent discharged from the regeneration tower, a first compression pump 114 for compressing the lean absorbent, The first cooler 115 may cool the first cooler 115.

A second compression pump 116 disposed in the third line 107 for compressing the semi-linin absorbent and a second cooler 117 for cooling the semi-linin absorbent.

The liquefied water is returned to the regeneration tower after the water contained in the acid gas discharged from the upper part of the regeneration tower is liquefied, and the acid gas, And a condenser 118 for discharging the condensed water.

The first and second absorbents of the first absorption tower 101 and the second absorption tower 102 may be amine absorbents comprising methyl diethanolamine.

The concentration of the first absorbent to which the acid gas has been adsorbed, moving from the first absorption tower 101 to the regeneration tower 103, may be from 0.5 to 0.8 mole-acid gas / mole-absorbent.

The concentration of the second absorbent with acidic gas adsorbed from the second absorption tower 102 to the absorbent mixer 104 may be 0.1 to 0.3 mole-acid gas / mole-absorbent.

The concentration of the less regenerated semi-lean sorbent flowing out in the middle of the regenerator 103 may be 0.3 to 0.5 mole-acid gas / mole-absorbent.

The concentration of the completely regenerated lean absorbent flowing out from the lower part of the regeneration tower 103 may be 0.01 to 0.1 mole-acid gas / mole-absorbent.

In the absorbent mixer 104, the semi-lean absorbent and the second absorbent to which the acid gas is adsorbed may be mixed at a weight ratio of 1-3: 1.

According to another aspect of the present invention, there is provided a method for removing acidic gas contained in natural gas, comprising the steps of: (A) adsorbing an acidic gas contained in natural gas supplied from a first absorber to a first absorber;

(B) moving the natural gas from which the acid gas has been partially removed to the second absorption tower to adsorb the acid gas contained in the natural gas with the second absorbent filled in the second absorption tower 102;

(C) discharging the natural gas treated with the second absorbent to the outside;

(D) transferring and regenerating the first absorbent to the regeneration tower;

(E) conveying a semi-lean absorbent partially leached out during regeneration of the regeneration tower to an absorbent mixer;

(F) transferring the second absorbent discharged from the second absorption tower to an absorbent mixer to mix with the semi-absorbent;

(G) transferring the mixed absorbent mixed in the absorbent mixer to the first absorption tower and using it as a first absorbent; And

(H) transferring the lean absorbent, which has been regenerated in the regeneration tower, to the second absorption tower and using the same as the second absorbent.

Condensing water contained in the acid gas discharged from the regeneration tower and conveying the water to the regeneration tower; And discharging the acid gas from which the moisture has been removed to the outside.

In the step (A), the concentration of the first absorbent to which the acid gas is adsorbed may be 0.5 to 0.8 mole-acid gas / mole-absorbent.

The concentration of the second absorbent to which the acid gas is adsorbed in the step (B) may be 0.1 to 0.3 mole-acid gas / mole-absorbent.

In step (E), the concentration of the less regenerated semi-lean absorbent flowing out during regeneration may be 0.3 to 0.5 mole-acid gas / mole-absorbent

The concentration of the lean absorbent that has been regenerated in step (H) may be 0.01 to 0.1 mole-acid gas / mole-absorbent

In step (F), the semi-sorbent absorbent and the second absorbent to which the acid gas is adsorbed may be mixed in a weight ratio of 1-3: 1.

The apparatus for removing acidic gas contained in natural gas according to the present invention is characterized in that acid gas is removed so that the concentration of acid gas contained in the natural gas is not more than 50 ppm carbon dioxide and not more than 3 ppm hydrogen sulfide, The two absorbing towers used reduce the thermal energy used for regenerating the absorbent in the regenerator by about 15% or more through efficient absorption of acid gas.

In order to sufficiently absorb the acid gas, the height of the absorption tower must be long. In the marine plant, since the structure is affected by the ship-motion, the distribution of the fluid flowing through the absorption tower becomes uneven The absorption of the acid gas is lowered. Accordingly, in the present invention, two absorption towers are provided so that acidic gas can be efficiently absorbed and removed without being affected by ship-motion.

FIG. 1 is a process flow diagram using an apparatus for removing acidic gas contained in natural gas produced according to an embodiment of the present invention.
2 is a process flow diagram using an apparatus for removing acidic gas contained in a conventional natural gas.

The present invention relates to an apparatus and a method for removing acidic gas contained in a natural gas, which can reduce the energy consumption by about 15% or more compared to the prior art while lowering the acid gas (including carbon dioxide and hydrogen sulfide) .

Hereinafter, the present invention will be described in detail with reference to Fig.

The apparatus for removing acidic gas contained in the natural gas of the present invention comprises a first absorption tower 101, a second absorption tower 102, a regeneration tower 103, an absorbent mixer 104, a first line 105, The acid gas can be removed by a continuous process including the second line 106, the third line 107, the fourth line 108 and the fifth line 109 as main devices.

The first absorption tower (101)

The first absorber 101 is filled with a first absorbent and is supplied with natural gas to a lower portion of the first absorber 101 to absorb the acidic gas contained in the natural gas, that is, carbon dioxide and hydrogen sulfide Thereby removing a part of the acidic gas contained in the natural gas.

Natural gas, which has been treated with the first absorbent and has been partially removed from the acid gas, is transferred to the lower portion of the second absorption tower 102 through the upper portion of the first absorption tower 101, and the first absorbent Is discharged from the lower part of the first absorption tower (101) and transferred to the regeneration tower (103).

The first absorbent filled in the first absorber 101 is an amine absorbent containing methyl diethanolamine in an amount of 40 to 60% by weight. When the content of the methyl diethanolamine is less than the lower limit, If it exceeds the upper limit value, corrosion and performance of other devices including the first absorption tower may be deteriorated.

The first absorbent for adsorbing the acid gas in the first absorption tower 101 is supplied from the absorbent mixer 104 and the concentration of the first absorbent for absorbing the acidic gas and moving to the regeneration tower 103 is 0.5 - The concentration of the first absorbent supplied from the absorbent mixer 104 (before the adsorption of the acid gas) is 0.3 to 0.5 mole-acid gas / mole-absorbent rather than the concentration of the first absorbent absorbed by the acid gas. / mole-absorbent low.

The second absorption tower (102)

The second absorption tower 102 is filled with a second absorbent and the natural gas processed in the first absorption tower 101 is supplied to the lower portion of the second absorption tower 101, A large amount of acidic gas contained in the gas is adsorbed so that the concentration of the acid gas contained in the natural gas is 50 ppm or less of carbon dioxide and 3 ppm or less of hydrogen sulfide.

The natural gas, which has been treated with the second absorbent to remove a large amount of acid gas, is discharged to the outside through the upper part of the second absorption tower 102. The second absorbent to which the acid gas is adsorbed is discharged from the second absorption tower 102, To the absorbent mixer 104 and reused as an acidic gas adsorbent in a non-regenerated state.

The second absorbent packed in the second absorption tower 102 uses the same adsorbent made of the same component as the first absorbent, but the first absorbent (before adsorption of the acidic gas) The mixed absorbent obtained by mixing the lean absorbent with the acidic gas absorbed second absorbent is used as the first absorbent, whereas the second absorbent (before absorbing the acidic gas) uses the completely absorbed lean absorbent by the regeneration tower as the second absorbent, The natural gas is sequentially treated with two different adsorbents to minimize the concentration of the acid gas.

That is, the first absorbent having a high concentration is firstly treated with natural gas to remove some acid gas contained in the natural gas and then further treated with a second absorbent having a low concentration to remove a large amount of the acid gas contained in the natural gas, The concentration of the acidic gas can be minimized.

The second absorbent for adsorbing the acid gas in the second absorption tower 102 is a lean absorbent completely regenerated in the regeneration tower 103. The concentration of the second absorbent (lean absorbent) before adsorption of the acid gas is 0.01 to 0.1 mole- acid gas / mole-absorbent, and the concentration of the second absorbent that absorbs the acid gas and moves from the second absorption tower 102 to the absorbent mixer 104 is 0.1 to 0.3 mole-acid gas / mole-absorbent. There is a difference of 0.1 to 0.2 mole-acid gas / mole-absorbent before and after adsorption of the acid gas.

Play Tower (103)

In the present invention, the regeneration tower 103, in which the absorbent is introduced for regeneration, is desorbed and regenerated as the absorbent introduced into the regeneration tower moves to the lower part of the regeneration tower. The less regenerated absorbent in the middle portion of the regeneration tower 103 on the other side of the middle portion and the two kinds of absorbents completely regenerated in the lower portion of the regeneration tower 103 are discharged.

The less regenerated sorbent is referred to as the semi-lean sorbent and is transferred to the sorbent mixer 104, which is referred to as lean sorbent and is used as the second sorbent in the second absorber 102.

The concentration of the first absorbent to which the acid gas is adsorbed into the regeneration tower 103 is 0.5 to 0.8 mole-acid gas / mole-absorbent, while the concentration of the less regenerated semi- 0.5 mole-acid gas / mole-absorbent, and the concentration of the completely regenerated lean absorbent is 0.01 to 0.1 mole-acid gas / mole-absorbent.

A condenser 118 is disposed above the regeneration tower 103 to liquefy the water contained in the acidic gas discharged from the upper part of the regeneration tower and return the liquefied water to the regeneration tower for reuse, The removed acid gas is discharged to the outside.

The absorbent mixer (104)

The absorbent mixer 104 is a device for providing a mixed absorbent to be used as the first absorbent of the first absorbent column 101. The absorbent mixer 104 includes a second absorbent to which the acid gas discharged from the second absorbent column 102 is adsorbed, The semi-lean absorbent discharged from the middle portion of the column 103 is mixed to prepare a mixed absorbent.

The mixed absorbent is an absorbent in which the semi-lean absorbent and the second absorbent are mixed at a weight ratio of 1: 3 to 1: 1, preferably 1: 1. When the content of the semi-linseed absorbent is less than the lower limit based on the second absorbent, the amount of the acidic gas to be removed may be insignificant when used as the first adsorbent because a low concentration of the semi-leaned absorbent is used. The amount of the absorbent regenerated in the regeneration tower is increased in order to produce the semi-lean absorbent, so that the energy is not saved.

In the absorbent mixer 104 of the present invention, a mixed absorbent in which a semi-lean absorbent slightly regenerated in the regeneration tower and a second absorbent not regenerated at all are prepared and used as a first absorbent, Energy can be saved because it is reused as an absorbent for the first stage treatment of acid gas without almost using it.

In the first line 105,

The first line 105 connects the lower part of the first absorption tower 101 and the intermediate part of the regeneration tower 103 to introduce the first absorbent discharged from the first absorption tower into the regeneration tower.

A flash drum 110 is disposed in the first line 105 and is operated under a condition of 7 to 8 bar to remove a part of methane and acid gas absorbed in the first absorbent.

In the second line 106,

The second line 106 connects the lower part of the regeneration tower 103 and the upper part of the second absorption tower 102 to introduce the lean absorbent regenerated in the regeneration tower into the second absorption tower, Used as absorbent.

A heat exchanger 111 is disposed at a position where the first line 105 and the second line 106 intersect to perform heat exchange between the first absorbent flowing into the regeneration tower and the lean absorbent discharged from the regeneration tower do. That is, by using the heat of the hot lean absorbent discharged from the regeneration tower, the first absorbent (the first absorbent absorbed by the acid gas) required to be regenerated to be introduced into the regeneration tower is preliminarily heated to consume less energy in the regeneration column.

Also, a reboiler 112 is disposed in the second line 106 to operate at 120 to 130 캜 under the same pressure as the regeneration tower to evaporate the acid gas and water contained in the lean absorbent discharged from the regeneration tower. The evaporated acid gas and water may be transferred to the regeneration tower.

In addition, the replenishing device 113 is disposed in the second line 106 to replenish the lean absorbent discharged from the regeneration tower with water lost during the process to maintain the amine concentration of the lean absorbent at a constant level, 114 is disposed to compress the lean absorbent, and a first cooler 115 is disposed to cool the hot lean absorbent.

The apparatus includes a reboiler 112, a heat exchanger 111, a replenishing device 113, a first compression pump 114, and a first cooler (not shown) in a second line 106 leading from the regeneration tower to the second absorption tower 115).

In the third line 107,

The third line 107 connects the middle portion of the regeneration tower with the absorbent mixer to introduce the slightly regenerated semi-lean absorbent into the sorbent mixer in the regeneration tower.

A second compression pump 116 is disposed in the third line 107 to compress the semi-linseed absorbent and a second cooler 117 to cool the hot semi-linseed absorbent.

In the fourth line 108,

The fourth line 108 connects the lower portion of the second absorption tower with the absorbent mixer, and introduces the second absorbent discharged from the second absorption tower into the absorbent mixer.

In the fifth line 109,

The fifth line 109 connects the absorbent mixer and the upper portion of the first absorption tower so that the mixed absorbent mixed in the absorbent mixer flows into the first absorption tower.

The present invention also provides a method for removing acidic gas contained in natural gas.

In the method of removing acidic gas contained in natural gas according to the present invention, acid gas contained in a natural gas flowing into a first absorbent of a first absorption tower is adsorbed to partially remove an acidic gas, And the second absorbent absorbs a large amount of the acidic gas contained in the natural gas to significantly lower the concentration of the acidic gas in the natural gas, and then discharges the natural gas having a lowered concentration of the acidic gas to the outside .

The first absorbent treated with the acid gas is transferred to the regeneration tower for regeneration. The regeneration tower regenerates a part of the absorbent (semi-lean absorbent) during the regeneration and transfers it to the absorbent mixer, The second absorbent to which the acidic gas has been adsorbed is transferred to the absorbent mixer and mixed with the semi-absorbent. The mixed absorbent mixed in the absorbent mixer is transferred to the first absorption tower and used as a first absorbent, and the regenerated lean absorbent in the regeneration tower is transferred to the second absorption tower and used as a second absorbent.

The method may further include the step of condensing water contained in the acid gas discharged from the regeneration tower and carrying it back to the regeneration tower, and discharging the acid gas from which the moisture has been removed to the outside.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the present invention. Such variations and modifications are intended to be within the scope of the appended claims.

Example  One.

As shown in Fig. 1, a first absorption tower 101 for firstly absorbing an acid gas of natural gas is operated at a condition of 67.4 bar, and natural gas treated in the first absorption tower is supplied to a second absorption tower And the second absorption tower 102, which is secondarily absorbed by the acid gas, is operated under the condition of 67.4 bar. The flash drum 110 is provided in the middle of the first absorber 101 for transferring the first absorbent that has adsorbed the acid gas to the regeneration tower 103 and is operated under the condition of 7.15 bar, Remove methane and some acid gases. The first absorbent that has passed through the flash drum is heated from the heat exchanger 111 and flows into the regeneration tower 103 operated at a pressure of 2 bar, thereby regenerating the acid gas. The moisture contained in the acid gas generated in the regeneration process is liquefied in the condenser 118 operated at a pressure of 2 bar and at a temperature of 50 ° C, and is returned to the regeneration tower, and the acidic gas from which moisture has been removed flows out.

The completely regenerated lean absorbent is operated at a pressure of 2 bar and at a temperature of 120 to 130 ° C to be treated with a reboiler 112 for generating water vapor so that the acid gas and water contained in the lean absorbent are evaporated, The evaporated phosphorus absorbent is fed through the heat exchanger and then supplied with water from the replenishing device 113 and compressed by the compression pump 114. The phosphorus absorbent is then cooled by the cooler 115 to cool the second absorbent 102 of the second absorption tower 102 .

The second absorbent in which the acid gas has been adsorbed in the second absorption tower 102 is conveyed to the absorbent mixer 104 where the less regenerated semi-lean absorbent in the regeneration tower 103 is compressed by the compression pump 116, (117) and transferred to the absorbent mixer (104) to be mixed with the second absorbent absorbed by the acid gas at a weight ratio of 1: 1. The mixed absorbent is used again as the first absorbent of the first adsorption tower (101).

The first and second absorbent MDEA is will contained 50% by weight, of a first absorbent semi-lean absorbent and sour gas are adsorbed second absorbent and 1 are mixed in a weight ratio of 1 900 Sm ³ / h, respectively and is used as a liquid volume.

Comparative Example  One.

2, an absorption tower 201 for absorbing an acid gas of natural gas is operated at a condition of 67.4 bar, and an absorbent for adsorbing acid gas in the absorption tower 201 is connected to the regeneration tower 204 A flash drum 202 is provided in the middle of the transfer of the adsorbent to operate at 7.15 bar to remove methane and some acidic gas contained in the absorbent. The absorbent that has passed through the flash drum 202 is heated from the heat exchanger 203 and flows into the regeneration tower 204 operated at a pressure of 2 bar, thereby regenerating acid gas. The moisture contained in the acid gas generated in the regeneration process is liquefied in the condenser 205 operated at a pressure of 2 bar and at a temperature of 50 ° C, and is returned to the regeneration tower, and the acidic gas from which moisture has been removed flows out to the outside.

The regenerated absorbent is operated at a pressure of 2 bar and a temperature of 120 to 130 ° C to be treated with a reboiler 206 for generating water vapor to evaporate the acidic gas and water contained in the absorbent, After the absorbent passes through the heat exchanger, moisture is supplied from the replenishing device 207, compressed by the compression pump 208, and then cooled by the cooler 209 to be used as the absorbent of the absorption tower 201 again.

The absorbent contains 50% by weight of MDEA, and 1,800 Sm ³ / h (liquid volume) is used.

< Test Example >

Test Example  1. Measurement of concentration and energy of acid gas

The following test was carried out on a ProMax simulator and the natural gas was supplied at 32 ° C and 67.5 bar at a flow rate of 5.27 × 10 ⁶ Sm ³ / h, and the natural gas had 15 mol% of carbon dioxide and 60 ppm of hydrogen sulfide . The diameters of the absorption towers used in the processes of Example 1 and Comparative Example 1 are the same as 4.8 m, and the diameter of the regeneration tower is equal to 6.0 m.

The amount of energy when treating the natural gas with the apparatus of Example 1 and Comparative Example 1 and the amount of carbon dioxide remaining in the actual natural gas and the amount of carbon dioxide remaining in the natural gas are controlled so that the concentration of carbon dioxide contained in the natural gas is 50 ppm or less and the concentration of hydrogen sulfide is 3 ppm or less. The concentration of hydrogen sulfide was measured.

division Energy rate (MW) Acid gas concentration (ppm) Rebid cooling water
(Condenser + absorbent cooling) Compression pump heat transmitter CO ₂ H ₂ S UA, MW / ° C NMDT, ° C Example 1 81.9 77.1 4.36 2.1 21.5 49.9 0.138 Comparative Example 1 116.2 111.5 4.56 3.7 19.0 49.9 0.192

As shown in Table 1 above, treating natural gas according to the process of Example 1 of the present invention can reduce carbon dioxide contained in natural gas to 49.9 ppm and hydrogen sulfide to 0.138 ppm in a small energy amount.

On the other hand, when natural gas was treated according to the process of Comparative Example 1, it was confirmed that hydrogen sulfide was present at a high concentration while using much energy as compared with Example 1.

100: Device for removing acidic gas contained in natural gas
101: first absorption tower 102: second absorption tower
103: regeneration tower 104: absorbent mixer
105: first line 106: second line
107: third line 108: fourth line
109: fifth line 110: flash drum
111: heat exchanger 112: re-boiling
113: replenishing device 114: first compression pump
115: first cooler 116: second compression pump
117: second cooler 118: condenser
200: Conventional device for removing acidic gas contained in natural gas
201: absorption tower 202: flash drum
203: heat exchanger 204: regenerator
205: condenser 206: re-boiler
207: Replenishing device 208: Compressing pump
209: Cooler

Claims (20)

A first absorption tower (101) for receiving natural gas through a lower portion and removing acidic gas contained in the natural gas with a first absorbent;
A second absorber (102) for receiving the natural gas discharged from the first absorber and discharged through the lower portion to remove residual acid gas contained in the natural gas with a second absorber;
A regeneration tower (103) for supplying and regenerating a first absorbent discharged through a lower portion of the first absorption tower through an intermediate portion;
An absorbent mixer (104) for mixing a second absorbent discharged through the lower part of the second absorption tower and a semi-lean absorbent discharged from the middle part of the regeneration tower;
A first line (105) connecting a lower portion of the first absorber and an intermediate portion of the regeneration tower to introduce a first absorbent discharged through a lower portion of the first absorber into the regeneration tower through an intermediate portion;
A second line (106) connecting the lower part of the regeneration tower and the upper part of the second absorption tower to introduce the lean absorbent regenerated in the regeneration tower and discharged through the lower part to the second absorption tower through the upper part;
A third line 107 connecting the intermediate portion of the regeneration tower and the absorbent mixer to introduce the semi-lean absorbent regenerated in the regeneration tower and discharged through the intermediate portion into the absorbent mixer;
A fourth line (108) connecting the lower portion of the second absorption tower and the absorbent mixer to introduce a second absorbent discharged through the lower portion of the second absorption tower into the absorbent mixer; And
And a fifth line (109) connecting the absorbent mixer and the upper portion of the first absorption tower to introduce the mixed absorbent mixed in the absorbent mixer into the first absorption tower through an upper portion thereof. An apparatus for removing acidic gas contained in a gas. 2. The method of claim 1, further comprising a flash drum (110) disposed in the first line (105) to remove a portion of the acid gas absorbed in the first absorbent. Removal device. The method of claim 1, further comprising: performing heat exchange between a first absorbent disposed at a position where the first line (105) intersects with the second line (106) and flowing into the regeneration tower and a lean absorbent discharged from the regeneration tower And a heat exchanger (111) for removing the acidic gas contained in the natural gas. 2. The method of claim 1, further comprising a re-boiler (112) disposed in the second line (106) to evaporate acidic gas and water contained in the lean absorbent discharged from the regenerator And removing the contained acidic gas. The system of claim 1, further comprising a replenishing device (113) for replenishing the lean absorbent disposed in the second line (106) and discharged from the regeneration tower during operation, a first compression pump 114) and a first cooler (115) for cooling the lean absorbent. The method of claim 1, further comprising a second compression pump (116) disposed in the third line (107) to compress the semi-linseed absorbent and a second cooler (117) to cool the semi-linseed absorbent And removing the acid gas contained in the natural gas. The method according to claim 1, further comprising: liquefying the water contained in the acidic gas disposed on the upper side of the regeneration tower (103) and discharging from the upper part of the regeneration tower, returning the liquefied water to the regeneration tower, Further comprising a condenser (118) for discharging the acidic gas to the outside. The method of claim 1, wherein the first and second absorbents of the first absorption tower (101) and the second absorption tower (102) are amine absorbents comprising methyl diethanolamine. Gas removal device. The method of claim 1, wherein the concentration of the first absorbent moving from the first absorption tower (101) to the regeneration tower (103) is 0.5 to 0.8 mole-acid gas / mole-absorbent. An apparatus for removing acid gases. 2. The method of claim 1, wherein the concentration of the second absorbent moving from the second absorption tower (102) to the absorbent mixer (104) is 0.1 to 0.3 mole-acid gas / mole-absorbent. An apparatus for removing acid gases. The apparatus of claim 1, wherein the concentration of the semi-sorbent sorbent flowing out of the regeneration tower (103) is 0.3 to 0.5 mole-acid gas / mole-absorbent. The apparatus for removing acidic gas according to claim 1, wherein the concentration of the lean absorbent flowing out from the lower portion of the regeneration tower (103) is 0.01 to 0.1 mole-acid gas / mole-absorbent. The method of claim 1, wherein the semi-phosphorus absorbent in the absorbent mixer (104) and the second absorbent absorbed acid gas are mixed in a weight ratio of 1-3: 1. Device. (A) adsorbing the acidic gas contained in the supplied natural gas with the first absorbent in the first absorption tower;
(B) moving the natural gas from which the acid gas has been partially removed to the second absorption tower to adsorb the acid gas contained in the natural gas with the second absorbent filled in the second absorption tower 102;
(C) discharging the natural gas treated with the second absorbent to the outside;
(D) transferring and regenerating the first absorbent to the regeneration tower;
(E) transferring the semi-lean absorbent partially leached out in the regeneration tower to the absorbent mixer;
(F) transferring the second absorbent discharged from the second absorption tower to an absorbent mixer to mix with the semi-absorbent;
(G) transferring the mixed absorbent mixed in the absorbent mixer to the first absorption tower and using it as a first absorbent; And
(H) transferring the lean absorbent, which has been regenerated in the regeneration tower, to the second absorber and using the lean absorbent as a second absorbent. 15. The method of claim 14, further comprising: condensing moisture contained in the acidic gas discharged from the regeneration tower and returning the water to the regeneration tower; And
And discharging the acid gas from which the moisture has been removed to the outside of the natural gas. 15. The method of claim 14, wherein the concentration of the first absorbent to which the acid gas is adsorbed in step (A) is 0.5 to 0.8 mole-acid gas / mole-absorbent. 15. The method of claim 14, wherein the concentration of the second absorbent to which the acid gas is adsorbed in step (B) is 0.1 to 0.3 mole-acid gas / mole-absorbent. 15. The method of claim 14, wherein the concentration of the semi-sorbent sorbent flowing out during regeneration in step (E) is 0.3 to 0.5 mole-acid gas / mole-absorbent. . 15. The method of claim 14, wherein the concentration of the lean absorbent that has been regenerated in step (H) is 0.01 to 0.1 mole-acid gas / mole-absorbent. 15. The method of claim 14, wherein in step (F), the semi-phosphorus absorbent and the second absorbent to which the acid gas is adsorbed are mixed at a weight ratio of 1-3: 1. .

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