JPH05337334A - Carbon dioxide gas removal treatment system of combustion exhaust gas - Google Patents

Abstract

PURPOSE:To remove carbon dioxide gas efficiently by allowing a combustion exhaust gas containing a small amount of a sulfur oxide to come in contact with an amine-based absorption liquid, then removing the carbon dioxide gas from the exhaust gas by absorption, and regenerate the amine-based absorption liquid by carbon dioxide gas removal. CONSTITUTION:Combustion exhaust gas containing about 100ppm max of sulfur oxide is introduced into an amine-based absorption column from a line 11, then a combustion exhaust gas is allowed to come in contact with the amine-based absorption liquid, and the carbon dioxide gas of the exhaust gas undergoes a chemical reaction with the amine-based absorption liquid remove the gas by absorption. A treated exhaust gas from which carbon dioxide gas is removed in the amine-based absorption column 1 is exhausted to an atmosphere. On the other hand, the amine-based absorption liquid in which the carbon dioxide gas is absorbed is extracted by a pump through a line 12 to be supplied to an absorption liquid regeneration process. Further, the amine-based absorption liquid is thermally regenerated in the first regeneration tower 2, and is circulated to the amine-based absorption column 1 through a line 22 as a regenerated absorption liquid. The carbon dioxide gas which is separated and desorbed in the first regeneration tower 2 is extracted through a line 21, then is sent to an outside area of the system through a gas/liquid separator, and finally is concentrated, recovered and hardened.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a system for decarbonating flue gas for absorbing and removing carbon dioxide from flue gas.

[0002]

2. Description of the Related Art In recent years, environmental pollution on a global scale has become a problem. In particular, global warming and the like caused by atmospheric accumulation of carbon dioxide gas emitted from the use of fossil fuels have become a problem. Therefore, the emission of carbon dioxide is on a global scale, and various proposals for suppressing the emission of carbon dioxide have been made. For example, various fuel conversion proposals, combustion methods and devices for reducing carbon dioxide gas generation, and carbon dioxide gas removal methods and devices have been proposed.

[0003]

However, the technology for suppressing the carbon dioxide emission on a global scale has just been started, and the technical development in the future is greatly borne. In view of the above situation, the inventors have particularly studied a method for simply and efficiently removing carbon dioxide gas in combustion exhaust gas from a large-scale boiler or the like, which is the largest cause of large-scale emission of carbon dioxide gas.
As a result, the present invention has been completed in which carbon dioxide gas can be efficiently removed from combustion exhaust gas by treating with an amine-based absorption liquid.

[0004]

According to the present invention, combustion exhaust gas having a small sulfur oxide content is brought into contact with an amine-based absorption liquid, and carbon dioxide gas in the exhaust gas is absorbed and removed by the amine-based absorption liquid. Provided is a decarbonation treatment system for combustion exhaust gas, which comprises an amine absorption process for discharging treated exhaust gas, and an absorption liquid regeneration process for regenerating by decarbonating the amine-based absorption liquid absorbing carbon dioxide gas. To be done.

[0005]

The present invention is constituted as described above, and by treating the combustion exhaust gas having a low sulfur oxide content in the amine absorption step, the carbon dioxide gas in the exhaust gas is reacted and absorbed in the amine-based absorption liquid, Carbon dioxide can be removed efficiently. Further, the amine-based absorbing liquid that has absorbed carbon dioxide can be recycled and reused. Further, by constructing the amine absorbing step from the predetermined dispersing means, gas / liquid contacting means, and gas discharging means, the system of the present invention can be made compact, and the combustion exhaust gas can be uniformly dispersed in the amine absorbing liquid. Can be blown in. Therefore, carbon dioxide gas in the exhaust gas can be efficiently removed. Furthermore, in the amine absorption step, a predetermined cooling means can be integrally provided, so that the combustion exhaust gas supplied at a high temperature can be cooled to a temperature suitable for amine absorption operation. It is possible to compactly carry out a series of operations of dispersion, contact with an amine-based absorbent and discharge.

It is preferred that the flue gas treated in the decarbonation system of the present invention has a low sulfur oxide content, ie, a relatively low amount of about 100 ppm or less. High sulfur oxide content, eg about 20
If it exceeds 0 ppm, the absorption capacity of the amine-based absorbing solution is significantly lowered, which is not preferable. Therefore, when a large amount of sulfur oxides such as sulfurous acid gas is contained in the treated combustion exhaust gas such as combustion exhaust gas of ordinary coal or petroleum-based fuel, in advance,
After the exhaust gas is desulfurized to reduce the sulfur oxides to the above concentration, it is preferably introduced into the decarbonation system of the present invention. The amine-based absorbent used in the present invention is
It is also deteriorated by sulfur compounds such as hydrogen sulfide other than sulfur oxides. However, most of the sulfur compounds in the combustion exhaust gas are sulfur oxides, and in the decarbonation gas treatment system of the present invention, the sulfur oxide content of the combustion exhaust gas to be introduced is regulated,
By suppressing the deterioration of the amine-based absorption liquid, it is possible to stably and continuously perform the decarbonation gas treatment.

In the treatment of combustion exhaust gas containing a large amount of dust and / or sulfur oxides such as petroleum or coal combustion exhaust gas, the present applicant has already disclosed in JP-A-1-159017 and JP-A-159027.
The desulfurization combustion exhaust gas treated by the dust removal and desulfurization treatment method of the flue gas proposed in No. 72913, No. 3-262510 etc. or other flue gas desulfurization treatment method is introduced into the decarbonation gas treatment system of the present invention. Is preferred. The combustion exhaust gas of LNG contains almost no sulfur oxide. Therefore, the LNG combustion exhaust gas can be directly introduced into the decarbonation gas treatment system of the present invention. Further, in the case of a combustion exhaust gas containing a relatively small amount of sulfur oxides and containing a relatively large amount of dust, in the amine absorption step of the present invention, dust removal is sufficiently performed by providing a cooling treatment means described later. Since it can be treated, it can be introduced into the decarbonation treatment system of the present invention as it is, like LNG combustion exhaust gas.

[0008]

Embodiments of the present invention will now be described in detail with reference to the drawings. However, the present invention is not limited to the following examples. FIG. 1 is a schematic explanatory diagram of a combustion exhaust gas decarbonation system according to an embodiment of the present invention, FIG. 2 is a vertical cross-sectional explanatory diagram of an embodiment of an amine absorption step in the decarbonation treatment system of the present invention, and FIG. It is a longitudinal section explanatory view of other examples of an amine absorption process. In FIG. 1, the decarboxylation gas treatment system comprises an amine absorption tower 1 and an absorption liquid regeneration step connected in series, and the absorption liquid regeneration step is composed of two stages of a first regeneration tower 2 and a second regeneration tower 3. Then, the combustion exhaust gas introduced into the system is decarbonated. For example, the combustion exhaust gas having a sulfur oxide content of about 100 ppm or less is introduced into the amine absorption tower 1 through the line 11, and the combustion exhaust gas and the amine absorption liquid are brought into contact with each other, so that carbon dioxide gas in the exhaust gas is converted into the amine absorption liquid. It reacts with L and is absorbed and removed. The treated exhaust gas that has been decarbonated in the amine absorption tower 1 is discharged to the outside. On the other hand, the amine-based absorption liquid that has absorbed carbon dioxide by reaction is preferably withdrawn by a pump through the line 12 and supplied to the absorption liquid regeneration step. The amine-based absorption liquid that has absorbed the carbon dioxide gas supplied to the absorption liquid regeneration step is basically heated and regenerated in the first regeneration tower 2 and circulated to the amine absorption tower 1 through the line 22 as the regenerated absorption liquid. The carbon dioxide gas separated and desorbed in the first regeneration tower 2 is extracted through a line 21, sent out of the system through a gas-liquid separator 4, and then sent to an appropriate treatment system for concentration and recovery.
Appropriate processing such as solidification is performed.

The decarbonation gas treatment system of the present invention treats combustion exhaust gas containing a small amount of sulfur oxides as described above. Therefore, the absorbing liquid of the present invention is hardly deteriorated by accumulation of impurities and the like except that the carbon dioxide gas absorption capacity is reduced. However, in the long-term combustion exhaust gas treatment, sulfur compounds, mainly sulfur oxides, may gradually accumulate in the amine-based absorption liquid. In such cases, the first
The regeneration treatment only with the regeneration tower does not sufficiently regenerate, and the absorption capacity of the amine-based absorbing solution gradually decreases. Therefore, in the present invention, a part of the regenerated absorption liquid circulated from the first regeneration tower 2 to the amine absorption tower 1 via the line 22 is preferably fed to the second regeneration tower 3 via the line 23 regularly or appropriately. It is better to introduce it and further treat it by heating distillation or the like. By the treatment in the second regeneration tower 3, the residual carbonic acid in the regeneration absorption liquid can be further desorbed and removed, and the impurities such as sulfur compounds and the like that are deteriorated can be separated and removed. In the second regeneration tower 3, a distillate absorption liquid, which is a light component containing a gas component such as carbon dioxide, is withdrawn through a line 31 from the top of the tower, and then the gas component (mainly carbon dioxide gas is passed through the gas-liquid separator 5). ) Is sent out of the system, a part of the liquid component is circulated to the second regeneration tower 3, and the rest is sent to the first regeneration tower 2 through the line 32. Meanwhile, the second
At the bottom of the regeneration tower 3, a heavy component in which the above impurities are concentrated to a high concentration is accumulated. It is preferable that the accumulated heavy components are appropriately extracted through the line 33, and then collected, discarded, or burned. In the present invention, the second regeneration tower 3
Does not need to be installed when the deterioration of the amine-based absorption liquid is small due to the properties of the combustion exhaust gas to be treated.

Next, the amine absorbing step of the present invention will be described. In FIG. 2, the amine absorption tower 1 is formed in a closed container structure as a whole, and includes an upper gas dispersion chamber A and a lower carbon dioxide gas absorption chamber B. The gas dispersion chamber A is composed of a top plate 41 of the amine absorption tower 1, a side wall 42, and a space partitioned by a horizontal partition wall 43 connected to the side wall 42. Further, a gas inlet 44 is provided on the side wall 42 of the gas dispersion chamber A, and the gas inlet 4
An exhaust gas introduction pipe 45 is connected to 4. Horizontal partition 43
Has a central opening, and a processing gas exhaust pipe 47 is connected to the opening 46. The processing gas discharge pipe 47 communicates with the carbon dioxide gas absorption chamber B and penetrates the amine absorption tower 1 to discharge the processing gas to the outside of the system. Further, the horizontal partition wall 43 has a large number of dispersion holes 48 on the plate surface, and a gas dispersion pipe 49 having a lower end opening is connected to each of the dispersion holes 48, and the amine-based absorption liquid retained in the carbon dioxide gas absorption chamber B is Let it hang down. As the gas dispersion pipe 49, a circular pipe body is usually used, but a pipe body having an arbitrary horizontal cross-sectional shape can also be used.

In the gas dispersion chamber A, a cooling water sprayer 51 communicating with the water distribution pipe 50 is arranged inside the gas introduction pipe 45 and / or above the horizontal partition wall 43 in the gas dispersion chamber A. be able to. The cooling water sprayer 51 can cool the combustion exhaust gas introduced into the gas introduction pipe 45 to bring the amine-based absorption liquid in the gas absorption chamber B to an appropriate absorption temperature. The cooling water sprayer 51 only needs to be able to spray the cooling water supplied by the water distribution pipe 50 as fine particles, and its size, form, etc. are not particularly limited. For example, a swirl type or jet type spray, a two-liquid nozzle, or the like can be used. Further, when the cooling water sprayer 51 is provided, the gas introduction pipe 45 may be installed so as to be tangential to the side wall 42. In this case, the exhaust gas is supplied into the gas dispersion chamber A while rotating, and the contact time between the cooling water particles sprayed from the sprayer 51 and the exhaust gas becomes long, and the cooling effect of the exhaust gas is enhanced, which is efficient.

In the present invention, the cooling water sprayer 51 may be arranged depending on the temperature of the combustion exhaust gas introduced and supplied. For example, if the combustion exhaust gas to be treated is a combustion exhaust gas of fossil fuel, flue gas desulfurization treatment is indispensable, and prior to the decarbonation gas treatment system of the present invention, desulfurization treatment is performed as a pretreatment in order to reduce the sulfur oxide content. In this case, the exhaust gas temperature is already about 50 ° C. or lower, which is the temperature suitable for use of a normal amine-based absorbent. Therefore, the gas dispersion chamber A
It is not necessary to provide the cooling water sprayer 51. Further, when the cooling water sprayer 51 is provided, the exhaust gas may be circulated in the gas dispersion chamber A to the dispersion holes 48 without being operated. Further, in the case of exhaust gas containing almost no sulfur oxides such as LNG combustion exhaust gas, desulfurization treatment is unnecessary, and the exhaust gas temperature introduced into the gas introduction pipe 45 is generally a high temperature of about 90 to 150 ° C. Therefore, an appropriate temperature according to the action of the absorbing liquid in the carbon dioxide gas absorbing chamber B, usually about 35 to 50
It is necessary to cool to a temperature of ° C. That is, the cooling water sprayer 51 is arranged in the gas introduction pipe 45 and / or the gas dispersion chamber A described above, and the cooling water supplied from the water distribution pipe 50 is ejected in the form of fine particles by the cooling water sprayer 51 to introduce the high temperature. The flue gas of Example 1 is cooled to a temperature suitable for the amine-based absorbent used. In this case, the number and arrangement position of the cooling water sprayers 51, the amount of cooling water jetted, the capacity of the sprayers, etc. are determined according to the exhaust gas temperature to be cooled, the cooling set temperature, and the exhaust gas flow rate.
Can be selected appropriately

In FIG. 2, the carbon dioxide absorption chamber B is located below the horizontal partition plate 43 of the gas dispersion chamber A, and has a side wall 42.
And a space formed by the bottom plate 52. Further, on the side wall forming the carbon dioxide gas absorption chamber B, a line 12 for discharging the absorption liquid to the absorption liquid in the first regeneration tower 2 of the absorption liquid regeneration process and a line 22 for circulating the absorption liquid in the amine absorption process are shown in FIG. It is arranged. The absorption liquid L is supplied and stored in the carbon dioxide gas absorption chamber B. The storage amount of the absorption liquid L has a predetermined space between the absorption liquid surface and the horizontal partition plate 43, and at the same time, as described above, in the gas dispersion pipe 49 hanging from the gas dispersion chamber A to the carbon dioxide gas absorption chamber B. It can be appropriately selected so that the lower end is located below the absorption liquid surface. The space between the horizontal partition plate 43 and the absorbing liquid surface may be appropriately selected depending on the capacity of the amine absorbing tower 1 and the degree of foaming of the absorbing liquid in the carbon dioxide gas treatment.

The lower end portion of the gas dispersion pipe 49 hanging down from the dispersion hole 48 of the gas dispersion chamber A is arranged with a predetermined space portion from the bottom plate 52 when the exhaust gas is ejected from the front end with the tip end being an opening. .. This is because the combustion exhaust gas flowing down through the gas dispersion pipe 49 can be ejected from the lower end portion of the opening into the absorbing liquid with a bubbling effect. Further, the lower end portion of the opening may be formed in a rectangular slit shape or a triangular slit shape to further enhance the bubbling effect. The spatial distance from the bottom plate 52 to the lower end of the gas dispersion pipe 49 can be appropriately selected according to the absorption operation conditions such as the amount of absorbed liquid stored, the amount of exhaust gas, the equivalent diameter of the gas dispersion pipe, and the number of arrangements. On the other hand, the gas dispersion pipe 49
Is the closed end, and a large number of exhaust gas outlet holes are formed in the pipe circumferential surface located at a predetermined distance from the closed lower end, for example, about 5 to 50 cm, and the exhaust gas is horizontally introduced into the absorption liquid of the carbon dioxide gas absorption chamber B. You may make it jet out to. In this case, it is not necessary to provide a specific space from the bottom plate 52. It is preferable to provide the above-mentioned exhaust gas outlet holes and jet the exhaust gas into the absorbing liquid in the horizontal direction in order to enhance the bubbling effect and the contact absorption efficiency. Furthermore, if necessary, a stirrer 53 may be installed in the absorption liquid in the carbon dioxide gas absorption chamber B to stir the absorption liquid.

In the amine absorbing step of the present invention configured as described above, the combustion exhaust gas supplied to the gas dispersion chamber A is used as it is or, if necessary, by the particulate cooling water sprayed from the cooling water sprayer 51. While being cooled, the top plate 4
After being blocked by 1 and descending toward the horizontal partition plate 43 and reaching the horizontal partition plate 43, it further passes through each dispersion hole 48, flows down through the gas dispersion pipe 49, and is dispersed in the carbon dioxide gas absorption chamber B. be introduced. Next, in the carbon dioxide gas absorption chamber B, the exhaust gas is dispersed in the amine-based absorption liquid through the blowout holes formed at the lower ends of the respective gas dispersion pipes 49 or on the peripheral surface as described above.
At the same time as being ejected, the exhaust gas efficiently contacts the absorbing liquid, and the carbon dioxide gas in the exhaust gas reacts with the amine component to be absorbed and removed. The treated exhaust gas from which the carbon dioxide gas has been absorbed and removed is discharged out of the system through the treated gas discharge pipe 47. In addition, before discharging from the processing gas discharge pipe 52 to the outside of the system, the scrubber 54
Can also be installed to remove the absorption liquid entrained in the processing gas.

The absorption liquid held in the carbon dioxide gas absorption chamber B is
Depending on the type of exhaust gas, processing conditions, etc., it can be appropriately selected from conventionally known alkanolamine-based absorption liquids for carbon dioxide. For example, a 15 to 35 wt% solution of monoethanolamine, diethanolamine, triethanolamine, diisopropanolamine or the like, or 60 to 70 wt% of diglycolamine or the like can be mentioned. In addition to the above amine, a corrosion inhibitor or an antifoaming agent may be added to the absorbing liquid, if necessary. These alkanolamines and other amine-based absorbents are suitable because the vapor pressure thereof is low at the absorption treatment temperature of about 30 to 50 ° C. and they are not entrained in the exhaust gas from the amine absorption step in a large amount.

The above alkanolamine and carbon dioxide gas react with each other at a molar ratio of 2: 1 to reach equilibrium. The absorption liquid that has reacted with carbon dioxide and has a reduced absorption capacity is sequentially withdrawn from the pipe 12 by a pump and sent to the first regeneration tower in the absorption liquid regeneration step,
It is regenerated by treating with carbon dioxide by heating. On the other hand, the first
The absorption liquid regenerated in the regeneration tower is circulated and supplied from the pipe 22 to the carbon dioxide gas absorption chamber B. In the present invention, by making the amount of the absorbing liquid extracted from the carbon dioxide gas absorbing chamber B and the circulating amount of the regenerated absorbing liquid substantially the same, the treatment operations are balanced and the carbon dioxide treatment of the combustion exhaust gas is continuously and stably performed. You can The amount of withdrawal and the amount of circulation of the absorption liquid can be appropriately selected depending on the amount of exhaust gas treated, the carbon dioxide gas concentration in the exhaust gas, and the amine concentration of the absorption liquid. In this case, if the amine concentration is increased, the circulation amount may be small, but there is a risk of corrosion of the device. On the other hand, when the amine concentration is low, the circulation amount becomes excessive, the load of the regeneration process and the circulation pump increases, and the apparatus becomes large. Therefore, in the known amine concentration range used for the above-mentioned ordinary carbon dioxide absorption treatment, the liquid load is set to a carbon dioxide / amine molar ratio of 0.35 to 0.35.
It is preferable to appropriately select it so as to be 0.8.

On the other hand, the treated exhaust gas discharged from the carbon dioxide absorption chamber B contains a large amount of water. For this reason,
In the gas dispersion chamber A, not only when the cooling water for cooling the target combustion exhaust gas is not sprayed, but also when the cooling water is sprayed and the cooling water is mixed in the carbon dioxide gas absorption chamber B, the amine-based absorption liquid is concentrated. Tend to be. In the decarbonation gas treatment operation of the present invention, the amine concentration of the amine-based absorption liquid in the carbon dioxide gas absorption chamber B is appropriately controlled so as to be maintained within the above predetermined range.

The amine absorption step of the decarbonation treatment system of the present invention is basically composed of the gas dispersion chamber A and the carbon dioxide gas absorption chamber B described above. In addition, the amine absorption step of another embodiment as shown in FIG. 3 can be adopted. In addition, in FIG. 3, the same reference numerals as those in the amine absorbing step shown in FIG. In FIG. 3, in the gas dispersion chamber A of the amine absorption step of FIG.
It is simply a cylindrical partition. ) 55, a cooling water collecting plate 56 that is continuously joined to the lower end of the cylindrical partition wall 55 and the side wall 42 is installed, and the gas distribution chamber A is formed by the cylindrical partition wall 55 and the cooling water collecting plate 56. Is divided into a cooling zone and a gas dispersion zone. The horizontal cross section of the tubular body forming the tubular partition wall 55 can take various shapes such as a circular shape, a semicircular shape, a square shape, and a rectangular shape.

The cylindrical partition wall 55 is normally opened at the upper end and the lower end, and connects the cooling region of the gas dispersion chamber A and the gas dispersion region. Further, the upper end of the cylindrical partition wall 55 may be closed, and an opening may be provided on the peripheral surface of the cylindrical portion to open laterally. The side openings can be any shape, such as circular, triangular, quadrangular and the like. Further, the uppermost opening of the gas introduction port 45 arranged on the side wall 42 of the amine absorption tower 1 is located below the upper end of the cylindrical partition wall 55, while the lowermost opening thereof is at the cooling water collecting plate 5.
Position above 6. A cooling water discharge pipe 57 is opened on the cooling water collecting plate 56, the cooling water discharge pipe 57 is connected to a water storage tank 58, and the cooling water in the tank 58 is a cooling water sprayer via a pump P and a pipe 50. Can be connected to 51.

In the gas dispersion chamber of the above system, the combustion exhaust gas introduced is cooled by the fine particle cooling water from the cooling water sprayer 51, flows over the cooling water collecting plate 56, and collides with the cylindrical partition wall 55. As a result, the cooling water and dust entrained in the exhaust gas are separated and an upward flow is obtained. Thereafter, the exhaust gas is shielded by the top plate 41, becomes a downward flow from the opening of the cylindrical partition wall 55, passes through the inside of the cylindrical partition wall 55, and then reaches the horizontal partition plate 43. The exhaust gas reaching the horizontal partition plate 51 passes through the respective dispersion holes 48 and descends through the gas dispersion pipe 49 in the same manner as in the amine absorption step of FIG.
Is jetted out and processed. This method efficiently cools the exhaust gas introduced into the gas dispersion chamber A when the exhaust gas to be treated has a high temperature or contains dust or the like,
It is effective for efficiently removing dust and the like. In this case, the upper end of the opening of the cylindrical partition wall 55 is arranged above the uppermost end of the exhaust gas introduction port 250 by 250 mm or more, and is arranged so as to have a space of at least 300 mm with the top plate 41 of the amine absorption tower 1. preferable. This is for sufficiently cooling the introduced combustion exhaust gas.

On the other hand, the particulate cooling water ejected from the sprayer 51 drops downward in the space of the cooling area, contrary to the upward flow of the exhaust gas, and is stored on the cooling water collecting plate 56, where it is cooled appropriately. It is extracted from the water discharge pipe 57, circulated to the cooling water sprayer 51 through the tank 58, the pump P and the pipe 50. Further, the cooling water that is accompanied by the exhaust gas and separated by the cylindrical partition wall 55 flows down through the cylindrical partition wall and is collected and stored on the cooling water collecting plate 56 together with the cooling water that has jetted out and dropped. The gas flow velocity in the cooling zone is a flow velocity at which the cooling water fine particles are not re-dispersed, for example, about 1 to 5 m / sec, both in the ascending and in the horizontal flow velocity.
Captured on top.

In the amine absorption tower 1 shown in FIG. 3, in order to highly maintain the cooling effect of the combustion exhaust gas and the separation effect of the cooling water fine particles ejected in the exhaust gas, and at the same time to make the entire apparatus compact, The cross-sectional area (X) in the tower where the horizontal partition plate 43 is located, the cross-sectional area (Y) of the lower end opening formed by the cylindrical partition wall 55, and the cross-sectional area (Z) of the processing gas discharge pipe 47 are as follows. It is preferable to have a relationship. That is, X−Y = P, Y−Z = Q, and 1 ≦ P / Q ≦ 5
And When P / Q is less than 1, the rising speed of the exhaust gas in the cooling region becomes excessively high, and the separation efficiency of the cooling water fine particles from the exhaust gas deteriorates. On the other hand, when P / Q exceeds 5,
The flow velocity of the gas flowing down the gas dispersion pipe 49 becomes excessively large, and the gas pressure loss increases, which is not preferable. The diameter of the gas dispersion pipe 49 is usually about 5 to 50 cm.

In the present invention, the amine absorbing step constituted as described above can be treated by connecting in two stages in series. In this case, the concentration of the amine-based absorbent in the first step of amine absorption is set to a normal concentration, and the concentration of the amine-based absorbent in the second step of amine absorption is extremely dilute, for example,
The concentration of the absorption liquid in the first stage is set to about 1/5 to 1/100, and the combustion exhaust gas to be treated is first introduced into the amine absorption process in the first stage,
The first-stage amine-treated exhaust gas discharged from the first-stage amine absorption process is introduced into the second-stage amine absorption process and treated. When the concentration of carbon dioxide gas in the combustion exhaust gas is high and it is necessary to increase the amine concentration of the amine-based absorption liquid above the normal concentration described above, the two-step amine absorption step described above is performed outside the amine component of the amine absorption liquid. It is effective in the case of remarkably reducing the volatilization and loss to the equipment, or in the case of reducing the circulation amount to make the apparatus compact.

[0025]

EFFECTS OF THE INVENTION In the combustion exhaust gas decarbonation treatment system of the present invention, for example, a large amount of low pressure combustion exhaust gas of 1,000,000 Nm 3 / hour is first treated in the amine absorption step configured as described above. In addition, dispersion of exhaust gas, cooling as required, and contact / absorption reaction with the absorbing liquid can be performed by one device, and the system can be made compact. Therefore, as compared with the conventional absorption method of high-pressure operation, the apparatus can be downsized in spite of operating at low pressure, and the cost of the apparatus can be significantly reduced. Further, the contact treatment between carbon dioxide gas in the exhaust gas and the amine absorbing liquid does not require the packed column used in the conventional amine absorbing step, and it is almost unnecessary to consider the pressure loss. This is industrially useful because it can be operated, the contact efficiency can be increased, and low-pressure operation can be performed, and running costs such as equipment cost and power cost can be reduced. Further, in the amine absorption step of the present invention, the exhaust gas to be treated can be effectively dispersed and ejected in the absorption liquid by a bubbling method to increase the contact efficiency between the exhaust gas and the amine-based absorption liquid. It is possible to efficiently perform the reaction absorption with the amine-based absorption liquid, and to increase the removal rate of carbon dioxide gas.

[Brief description of drawings]

FIG. 1 is a schematic explanatory diagram of an embodiment of the present invention.

FIG. 2 is a vertical cross-sectional explanatory view of one embodiment of the amine absorbing step of the present invention.

FIG. 3 is an explanatory cross-sectional view of another embodiment of the amine absorbing step of the present invention.

[Explanation of symbols]

1 Amine Absorption Tower 2 First Regeneration Tower 3 First Regeneration Tower 4, 5 Gas-Liquid Separator 12, 22, 50 Piping Line A Exhaust Gas Dispersion Chamber B Carbon Dioxide Absorption Chamber L Absorption Liquid P Pump 41 Top Plate 42 Side Wall
43 horizontal partition plate 44 gas inlet port 45 exhaust gas inlet pipe
46 Opening 47 Processed gas discharge pipe 48 Dispersion hole
49 Gas Dispersion Pipe 51 Cooling Water Sprayer 52 Bottom Plate
53 Stirrer 54 Scrubber 55 Cylindrical vertical partition
56 Cooling Water Collection Plate 57 Cooling Water Discharge Pipe 58 Water Storage Tank

Claims (5)

[Claims] 1. An amine absorption step of contacting combustion exhaust gas having a small sulfur oxide content with an amine-based absorption liquid, and absorbing and removing carbon dioxide gas in the exhaust gas with the amine-based absorption liquid to discharge treated exhaust gas. A decarbonation treatment system for combustion exhaust gas, which comprises a step of regenerating an absorption liquid that has absorbed carbon dioxide gas by decarbonation gas treatment and regeneration. 2. The amine absorption step comprises at least (1)
A gas dispersion means for converting the introduced exhaust gas into a downward flow and supplying it to a large number of hanging gas dispersion pipes, and (2) holding an amine-based absorbing solution and immersing it in the amine-based absorbing solution. 2. The combustion exhaust gas according to claim 1, further comprising: a gas / liquid contact means for introducing the exhaust gas into the absorption liquid from the gas dispersion pipe, and (3) a discharge means for discharging the exhaust gas in contact with the absorption liquid. Decarbonation system. 3. The decarbonation treatment system for combustion exhaust gas according to claim 2, wherein the amine absorption step further has a cooling treatment means for ejecting a particulate cooling liquid into the introduced exhaust gas. 4. The decarbonation gas of combustion exhaust gas according to claim 3, wherein the cooling treatment means is configured to eject the cooling liquid and convert the exhaust gas into an upward flow while separating and collecting the particulate cooling liquid. Processing system. 5. The absorption liquid regeneration step comprises first and second two-step steps, wherein the absorption liquid from the amine absorption step is heat-treated in the first regeneration step to regenerate the absorption liquid, and then the first step. The regenerated absorption solution is circulated from the first regeneration step to the amine absorption step, and a part of the circulation absorption solution is further heat-treated in the second regeneration step to discharge heavy components and light fractions to the first regeneration step. The decarbonated gas treatment system for flue gas according to any one of claims 1 to 4, wherein