KR20170114802A - Apparatus and method for carbon dioxide capturing by reusing the stripper`s overhead vapor thermal energy - Google Patents

Abstract

The present invention relates to a process for collecting carbon dioxide by recycling thermal energy of steam on a stripping tower and its object is to reduce the consumption of heat energy required for the regeneration of the absorbent, The present invention also provides a process for collecting carbon dioxide which recycles the thermal energy of steam on a stripping tower,
In the present invention, the absorbent having absorbed carbon dioxide through the absorption tower is firstly preheated by heat exchange with the overhead vapor generated in the deairing tower, and the first preheated absorbent (carbon dioxide absorption) is regenerated again in the deairing tower The second regeneration heat is exchanged with the regenerated absorbent (carbon dioxide separated absorbent) supplied to the absorption tower, and then the second preheating is conducted to the deodorization tower to reduce the consumption of renewable energy in the deodorization tower, Respectively.

Description

Technical Field [0001] The present invention relates to a process for recovering thermal energy of vapor over a stripping tower,

The present invention relates to a process for collecting carbon dioxide which recycles the thermal energy of steam on a stripping tower and an apparatus therefor. The sorbent discharged from the bottom of the absorption tower after being combined with carbon dioxide is subjected to primary preheating by high- A carbon dioxide capture step capable of reducing the consumption of the regenerated energy in the stripping tower by allowing the temperature of the absorbent to be secondarily preheated by the high temperature absorbent regenerated in the stripping tower and then being introduced into the stripping tower, .

In general, greenhouse gases are responsible for keeping solar heat in the atmosphere. Efforts are being made to reduce these greenhouse gases worldwide. In order to reduce greenhouse gases, Carbon Dioxide Capture & Storage (CCS) Research on technology is actively under way.

The carbon dioxide capture and storage (CCS) technology is a technology to isolate carbon dioxide emitted from mass emission sources such as power plants, steel and cement plants from the atmosphere due to the use of fossil fuels. It is divided into 'Postcombustion technology', 'Pre-combustion technology' and 'Oxy-fuel combustion technology'.

Among them, the post-combustion trapping techniques include absorption, adsorption, membrane separation, and deep-sea cooling. Among them, the chemical absorption method in which monoethanolamine (MEA) is used to absorb and capture carbon dioxide in natural gas or flue gas is most widely used ought.

In the chemical absorption method using the MEA, carbon dioxide is absorbed into the MEA by the contact between the MEA and the flue gas in the absorption tower, and the rich-MEA (rich-MEA) in which the carbon dioxide is absorbed is supplied to the demolition tower, The lean-MEA is regenerated into Lean-MEA (Lean-MEA) by releasing carbon dioxide gas, and the regenerated Lean-MEA is again supplied to the absorption tower to be contacted with the flue gas in the absorption tower. Carbon dioxide (CO2) in the flue gas is collected, separated, and purified by the MEA circulation between the absorption tower and the stripping tower.

However, since the chemical absorption method using the MEA requires a large amount of renewable energy to be supplied to the rich-MEA introduced into the stripping column in order to regenerate the lean-MEA in the stripping column, there is a problem of high renewable energy consumption for regeneration of the MEA There is a problem that the process cost is increased.

In addition, the overhead vapor generated in the deairing tower, that is, the overhead vapor containing carbon dioxide, has a high temperature due to the renewed energy in the deairing tower, but there is a side to go directly to the condenser without using any heat.

Published Patent Publication No. 10-2014-0042088 (Apr. 04, 2014)

It is an object of the present invention to provide a carbon dioxide capture process and a device for recycling heat energy of a stripping tower vapor which can reduce the consumption of heat energy required for regeneration of an absorbent and which can provide an environment suitable for the carbon dioxide removal reaction .

In the present invention, the absorbent having absorbed carbon dioxide through the absorption tower is firstly preheated by heat exchange with the overhead vapor generated in the deairing tower, and the first preheated absorbent (carbon dioxide absorption) is regenerated again in the deairing tower The second regeneration heat is exchanged with the regenerated absorbent (carbon dioxide separated absorbent) supplied to the absorption tower, and then the second preheating is conducted to the deodorization tower to reduce the consumption of renewable energy in the deodorization tower, Respectively.

In the present invention, the absorbent absorbed carbon dioxide is preliminarily heated by heat exchange in the first and second heat exchangers, the temperature is raised to 100 ° C or more, and then the carbon dioxide is introduced into the deodorization tower. , Thereby improving the process energy efficiency.

In the present invention, since the high-temperature overhead vapor generated in the stripping tower is supplied to the first heat exchanger to be heat-exchanged before flowing into the condenser, useful heat energy of the overhead vapor can be efficiently utilized.

Further, in the present invention, the absorbent absorbed with carbon dioxide is subjected to the first preliminary heating by the overhead vapor and then the second preliminary heating by the regenerated absorbent, so that the thermal energy of the overhead vapor and the heat energy of the regenerable absorbent can be utilized efficiently In addition, the temperature of the absorbent absorbed by carbon dioxide can be raised to 100 ° C or more within a short time through efficient heat exchange according to the temperature difference between the absorbent absorbed with carbon dioxide and the overhead vapor, and the temperature difference between the first preheated absorbent and the regenerated absorbent. So that it is possible to facilitate the entire process design.

In addition, the present invention is adapted to recycle the overhead vapor heat, thereby reducing the heat duty of the reboiler and cooling the overhead vapor. Condenser Heat Duty can also be reduced.

In addition, the present invention has many effects such that the absorbent absorbing the carbon dioxide is introduced into the deodorizing tower in a state in which the temperature is sufficiently raised through two preliminary heating, thereby reducing the heat duty that the reboiler should bear.

BRIEF DESCRIPTION OF THE DRAWINGS Figure 1 is an exemplary block diagram of a process according to the present invention.
FIG. 2 is a schematic view of an apparatus showing an overall process according to the present invention.

FIG. 1 is a block diagram showing a process according to the present invention, FIG. 2 is a diagram illustrating an example of a device showing an entire process according to the present invention,

In the present invention, the absorbent having absorbed carbon dioxide through the absorption tower is firstly preheated by heat exchange with the overhead vapor generated in the deairing tower, and the first preheated absorbent (carbon dioxide absorption) is regenerated again in the deairing tower The recovered absorbent (carbon dioxide separated absorbent) supplied to the absorption tower is heat-exchanged to be secondarily preheated and then introduced into the stripping tower to reduce the consumption of renewable energy in the stripping tower, Is smoothly reproduced.

That is, the present invention includes a carbon dioxide absorbing step of contacting a flue gas (100) containing carbon dioxide with an absorbent in an absorption tower (30); A primary preliminary heating step in which the absorbent having absorbed carbon dioxide is supplied to the first heat exchanger (10) and subjected to primary heat exchange with the overhead vapor (200) of the deodorizer (40); The absorbent that has been heat-exchanged in the first heat exchanger 10 is supplied to the second heat exchanger 20 and separated from the carbon dioxide through the high temperature steam of the reboiler 50 in the demolition tower 40, A second preliminary heating step of performing a second heat exchange with the regenerated absorbent supplied to the second preliminary heating step; A regeneration step of supplying a secondary preheated absorbent through the second heat exchanger (20) to the stripping tower (40) and dividing the recovered absorbent by separation of carbon dioxide and carbon dioxide; An absorbent circulation step in which the absorbent regenerated in the stripping tower (40) is supplied to the absorption tower (30) and circulated; An overhead vapor transfer step of supplying overhead vapor (200) containing carbon dioxide in a demixing tower to the condenser (41) after heat exchange through the first heat exchanger (10); And a collecting step in which the overhead vapor is cooled by the condenser 41 and separated from the reflux drum 42 by condensed water, condensed absorbent and carbon dioxide to collect carbon dioxide, The change in the amount of heat of the reboiler 50, and the change in the amount of heat of the condenser 41, thereby improving the energy efficiency of the entire process.

Examples of the absorbent include amine type compounds such as MEA (Monoethanolamine), DEA (Diethanolamine), MDEA (Methyl diethanolamine) and TEA (Triethanolamine), or amine type compounds, And a concentration of 50 wt% is used.

Hereinafter, the absorbent according to the present invention will be described in detail with MEA (monoethanolamine), carbon dioxide-absorbed absorbent as 'Rich-MEA' and carbon dioxide separated absorbent as Lean-MEA. This is for the purpose of helping understanding of the present invention, and the absorbent described in the present invention is not limited to MEA. However, the absorbent according to the present invention preferably uses an amine-based absorbent.

The carbon dioxide absorbing step absorbs carbon dioxide in the flue gas 100 by contacting the flue gas 100 with the MEA in the absorption tower 30. The carbon dioxide absorbing step absorbs carbon dioxide in the flue gas 100 by contacting the MEA -MEA) is injected in a solution state, the flue gas 100 flows in the upper end direction from the lower end of the absorption tower 30, and carbon dioxide in the combustion gas is absorbed into the MEA by countercurrent contact of the flue gas with the MEA.

The rich-MEA, in which carbon dioxide has been absorbed, is discharged through the lower end of the absorption column 30 to the first heat exchanger 10, Lt; / RTI >

In the first preliminary heating step, the temperature of the rich-MEA is increased by preheating the MEA absorbed by carbon dioxide by the overhead vapor 200 of the stripping tower before the MEA is introduced into the stripping tower 40,

The rich-MEA discharged to the bottom of the absorption tower 30 flows into the first heat exchanger 10 and the high-temperature overhead vapor 200 discharged from the top of the stripping tower 40 flows into the condenser 41 Is supplied to the first heat exchanger (10), and the rich-MEA is preliminarily heated by heat exchange with the rich-MEA in the first heat exchanger (10).

That is, the carbon dioxide absorption reaction in the absorption tower 30 is an exothermic reaction, and the rich MEA discharged to the lower end of the absorption tower 30 is maintained at about 50 to 56 DEG C, and the carbon dioxide separation Since the reaction is an endothermic reaction and the overhead vapor 200 discharged to the top of the stripping column 40 maintains a high temperature of about 90 to 120 DEG C, By heat exchange, the rich-MEA is preheated and raised to a temperature in the range of about 68-80 < 0 > C.

The second preliminary heating step is a step in which the rich pre-heated Rich-MEA in the range of about 68 to 80 DEG C by heat exchange in the first heat exchanger 10 is separated from the carbon dioxide by the high temperature steam of the reboiler 50 And the heat is exchanged in the second heat exchanger 20 by the lean-MEA supplied to the absorption tower 30.

That is, the lean-MEA supplied to the absorption tower 30 maintains a high temperature of about 100 to 120 ° C., and the first preheated Rich-MEA (about 68 to 80 ° C.) flows into the second heat exchanger 20 Absorbing the heat of the lean-MEA at a temperature of about 100 ° C or more and flowing into the demolition tower 40.

As described above, in the present invention, the rich-MEA is subjected to first and second preliminary heating by efficient heat exchange according to a temperature difference of 30 ° C or more, so that the temperature of the rich- (40) can be operated at a higher temperature, so that the environment in the demixing column is formed as an environment suitable for the endothermic reaction.

The regeneration step is a step of heating the rich-MEA introduced into the stripping tower 40 and separating it into carbon dioxide and Lean-MEA. The rich-MEA is maintained at a temperature of about 100 ° C or more by the second heat exchanger 20, Is supplied into the stripping tower 40 and then heated by steam heat energy supplied into the stripping tower through the reboiler 50 to be separated into carbon dioxide and Lean-MEA, thereby regenerating the MEA.

At this time, the thermal energy supplied into the deodorizer 40 through the reboiler 50 is supplied at a temperature lower than about 120 ° C so as not to cause deterioration of the MEA. That is, according to the present invention, the rich-MEA introduced into the stripping tower 40 has a temperature of 100 ° C or more by first and second preliminary heating and is supplied into the stripping tower 40 through the reboiler 50 Even if the thermal energy is lower than 120 캜, the separation reaction of carbon dioxide in the deodorization tower 40 is smoothly performed.

The lean-MEA regenerated in the stripping column 40 is circulated through the second heat exchanger (not shown). The lean-MEA is regenerated in the stripping column 40, 20), cooled to about 68 to 80 占 폚 by heat exchange with the first preheated Rich-MEA in the second heat exchanger 20, and then cooled to 40 占 폚 Is further cooled and supplied to the absorption tower (30).

In other words, the present invention is characterized in that the lean-MEA at 100 to 120 ° C is cooled to about 68 to 80 ° C by efficient heat exchange in the second heat exchanger 20, A separate cooler 83 is provided in the supply line 82 to lower the temperature of the Lean-MEA supplied into the absorption tower 30 to about 40 ° C. This is due to the fact that the condenser temperature of the absorber is considered at 40 ° C in consideration of the case where seawater is used as cooling water.

Further, the absorbent supply line 82 may further include a reservoir 84, which has a makeup function of MEA and water (H ₂ O).

In the overhead vapor transfer step, a high temperature overhead vapor (200) containing carbon dioxide discharged to the upper end of the stripping tower (40) is supplied to the first heat exchanger (10) Exchanged with the rich-MEA flowing into the heat exchanger 10, and the overhead vapor whose temperature is lowered by heat exchange is supplied to the condenser 41. [

At this time, the overhead vapor discharged to the upper end of the stripping tower 40 is cooled to about 70 ° C by heat exchange with the rich-MEA in the first heat exchanger, and then supplied to the condenser 41 do.

After the overhead vapor is cooled by the condenser 41, the collecting step is separated and collected in the reflux drum 42 as condensed water, condensed absorbent, and carbon dioxide. Since the collecting step corresponds to a known technique, a detailed description thereof will be omitted.

According to the above-described carbon dioxide capture process, the present invention can remove about 90% or more of carbon dioxide in the flue gas.

As described above, according to the present invention, the rich amine stream (Rich-MEA), which is the reaction product of carbon dioxide (CO ₂ ) and MEA, is discharged from the stripping tower 40 before entering the stripping tower 40 in the absorption tower 30 MEA preheated by high-temperature overhead vapor (200) and high-temperature lean-MEA regenerated in the demoulding tower (40) to be introduced into the demoulding tower (40) while maintaining a high temperature And the demoulding tower 40 can be operated more efficiently.

That is, the present invention is advantageous in that the consumption of the regenerated energy in the deodorizer 40 is reduced, the heat duty of the reboiler 50 is reduced, and the condenser, which is required to cool the overhead vapor, Since the condenser duty of the heat exchanger 41 is also reduced, the process energy efficiency as a whole is improved.

FIG. 2 is a view illustrating an example of an apparatus showing an entire process according to the present invention. The carbon dioxide collecting apparatus according to the present invention includes an absorption tower 30 into which flue gas containing carbon dioxide flows and is supplied with an absorbent, Absorbing agent absorbed in carbon dioxide absorbed in the absorption tower 30 and connected to the first vapor discharge line 71 of the stripping tower 40 and connected to the overhead vapor 200 by the first flow path 61, A first heat exchanger 10 connected to the absorbent outlet of the first heat exchanger 10 by a second flow path 62 so that the first preheated absorbent is introduced by the first heat exchanger 10, A second heat exchanger 20 connected to the absorbent discharge line 81 of the stripping tower 40 and supplied with regenerated absorbent and a second heat exchanger 20 connected to the absorbent outlet of the second heat exchanger 20 and the third flow path 63 The second preheated absorbent is introduced by the second heat exchanger 20, and the heat energy is supplied through the reboiler 50 An absorber supply line 82 connected to the regenerated absorber outlet of the second heat exchanger 20 to supply the regenerated absorbent to the absorber 30, a first heat exchanger 10, A condenser 41 which is connected to the overhead vapor outlet of the condenser 41 by a second vapor discharge line 72 and into which the overhead vapor whose temperature has been lowered by the first heat exchanger 10 is introduced, And a reflux drum (42).

The circulation of the absorbent and the regenerated absorbent is performed by a pump. The installation of such a pump is well known in the art, and a description thereof will be omitted.

Further, the present invention may further include a cooler, a condenser, and a storage tank connected to the first, second, and third flow paths, the first and second vapor discharge lines, the absorbent discharge line, the absorbent supply line, the absorption tower, The addition of the same configuration adds known technology, so a description thereof will be omitted.

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

Example 1

The lean-MEA, in which the rich-MEA in which carbon dioxide is absorbed through the absorption tower is heat-exchanged by the overhead vapor generated in the stripping tower and is first preheated, and the first preheated Rich-MEA is supplied from the stripping tower to the absorption tower Exchanged to be secondarily preheated, and then introduced into the stripping tower to collect carbon dioxide in the flue gas.

At this time, the absorption tower and the stripping tower were subjected to a process simulation under the conditions shown in Table 1 below. During the collection process, the heat exchange medium (Rich-MEA and overhead vapor) of the first heat exchanger and the heat exchange medium 1 The pre-heated Rich-MEA and Lean-MEA) in / out temperatures were measured and the results are shown in Table 2.

[Table 1]

[Table 2]

As shown in Table 2 above, the present invention is characterized in that the temperature of the rich-MEA discharged from the absorption tower through the first and second preheating is introduced into the de-stripping tower at a temperature of about 104 ° C, and the overhead vapor of the de- 70 ° C and supplied to the condenser. The lean-MEA supplied to the absorption tower from the stripping tower is lowered to about 72.1 ° C and supplied to the absorber at a temperature of about 40 ° C through the additional cooler.

Example 2

The carbon dioxide capture amount and the calorific value of the reboiler were measured by the collecting process according to Example 1, and compared with the control group, and the results are shown in Table 3.

In the contrast group, one heat exchanger is installed between the absorption tower and the stripping tower, and carbon dioxide in the flue gas is collected by a collection process configured to heat-exchange the rich-MEA in which the carbon dioxide is absorbed by the heat exchanger and the lean- It is a structure to collect.

[Table 3]

As can be seen from the above Table 3, the present invention shows that the heat change of the reboiler is reduced by about 7% as compared with the control group. Thus, the present invention can improve the regeneration of the MEA in the de- And the energy efficiency is increased.

It will be understood by those skilled in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined in the appended claims and their equivalents. Of course, such modifications are within the scope of the claims.

(10): first heat exchanger (20): second heat exchanger
(30): absorption tower (31): condenser
(40): demounting tower (41): condenser
(42): Refux drum (50): Reboiler
(61): first flow path (62): second flow path
(63): third flow path (71): first vapor discharge line
(72): second vapor discharge line (81): absorbent discharge line
(82): absorbent supply line (83): cooler
(84): Storage tank (100): Flue gas
(200): overhead vapor

Claims (5)

The absorbent having absorbed carbon dioxide through the absorption tower is firstly preheated by heat exchange with the overhead vapor generated in the demixing tower and the primary preheated absorbent is recovered from the regenerated Heat exchanged with the absorbent to be secondarily preheated, and then introduced into the deodorization tower, thereby reducing the consumption of renewable energy in the deodorization tower, and separating the carbon dioxide and the absorbent smoothly. Recycling CO2 capture process.
The method of claim 1,
In the carbon dioxide capture step,
A carbon dioxide absorption step of bringing a flue gas (100) containing carbon dioxide into a countercurrent contact with the absorbent in the absorption tower (30);
A primary preliminary heating step in which the absorbent having absorbed carbon dioxide is supplied to the first heat exchanger (10) and subjected to primary heat exchange with the overhead vapor (200) of the deodorizer (40);
The absorbent that has been heat-exchanged in the first heat exchanger 10 is supplied to the second heat exchanger 20 and the second absorbent that is subjected to the second heat exchange with the regenerated absorbent supplied from the demoulding tower 40 to the second heat exchanger 20 Heating step;
A regeneration step in which the secondary preheated absorbent is introduced into the stripping tower 40 through the second heat exchanger 20 and heated by the heat energy supplied through the reboiler to separate the carbon dioxide and the absorbent;
An absorbent circulation step in which the absorbent regenerated in the stripping tower 40 is heat-exchanged via the second heat exchanger 20 and then supplied to the absorption tower 30 and circulated;
An overhead vapor transfer step of supplying overhead vapor (200) containing carbon dioxide in a demixing tower to the condenser (41) after heat exchange through the first heat exchanger (10);
And a collecting step in which the overhead vapor is cooled by the condenser 41 and separated from the reflux drum 42 by the condensed water, the condensed absorbent, and the carbon dioxide,
The energy efficiency of the entire process is improved through the regenerated energy of the stripping tower 40, the change in the amount of heat of the reboiler 50, and the change in the amount of heat of the condenser 41, Carbon dioxide capture process.
The method according to claim 1 or 2,
Wherein the rich-MEA has a high temperature of 100 ° C or higher by first and second preliminary heating, and is introduced into the deodorization tower, and the step of collecting the carbon dioxide which recycles the thermal energy of the steam on the stripping tower.
The method of claim 2,
Wherein the thermal energy supplied into the stripping tower (40) through the reboiler is supplied at a temperature lower than 120 ° C so as not to cause deterioration of the MEA, thereby recovering the thermal energy of the vaporized steam.
An absorption tower (30) into which flue gas containing carbon dioxide flows and which is supplied with an absorbent,
The absorbent absorbed by the carbon dioxide in the absorption tower 30 is connected to the lower end of the absorption tower by the first flow path 61 and connected to the first steam discharge line 71 of the stripping tower 40, A first heat exchanger (10) to which the first heat exchanger (200)
The first absorbent outlet of the first heat exchanger 10 is connected to the second flow path 62 so that the first preheated absorbent is introduced by the first heat exchanger 10 and the absorbent discharge line A second heat exchanger (20) connected to the adsorbent (81) and supplied with the regenerated absorbent,
The absorbent outlet of the second heat exchanger 20 is connected to the third flow channel 63 so that the second preheated absorbent is introduced by the second heat exchanger 20 and the heat energy is supplied through the reboiler 50 A demounting tower 40,
An absorber supply line 82 connected to the regenerated absorber outlet of the second heat exchanger 20 to supply regenerated absorber to the absorber 30,
A condenser 41 connected to the overhead vapor outlet of the first heat exchanger 10 by the second vapor discharge line 72 to receive the overhead vapor whose temperature is lowered by the first heat exchanger 10,
And a reflux drum (42) connected to the condenser (41). The apparatus according to claim 1 or 2, wherein the condenser (41) is a condenser (41).

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