JP3381390B2 - Carbon dioxide capture device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to carbon dioxide (hereinafter referred to as "CO ₂ ") in exhaust gas discharged from a combustion device such as a boiler.
That. ) For recovering CO ₂ . 2. Description of the Related Art In recent years, environmental destruction at a global level, such as climate warming due to the greenhouse effect of artificially emitted CO ₂ and destruction of the ozone layer by stable compounds such as chlorofluorocarbons, has become a problem. Has become. Of these, CO associated with global warming
_When considering the _two problems, there are various CO ₂ emission sources, but it is hard to imagine that all of them can be dealt with by the same technology. For the time being, it has been proposed to treat large amounts of CO ₂ emitted from one place, specifically from combustion equipment provided in power plants, steel mills, cement industries, chemical complexes, etc., for example, emissions from boilers. Since the combustion exhaust gas contains a large amount of CO ₂ , attempts have been made to separate and recover the CO ₂ in the gas before discharging the combustion exhaust gas to the atmosphere. [0003] Dry and wet absorption methods are known as methods for removing CO ₂ , and the use of a wet absorption method which is advantageous in terms of efficiency and cost in gas treatment is being studied. Absorption method of the wet process, and a gas containing absorbing solution and CO _2, such as an alkanolamine solution by contacting the gas-liquid, but for absorbing and removing CO ₂ in the gas to the absorbing liquid. [0004] By the way, as shown in FIG. 2, the flue gas from a combustion device such as a boiler is discharged from a boiler 1 and flows through a flue gas duct 3, first of all, in an electric precipitator 4 where the gas is discharged. Dust is removed and the dust is removed. Then, after being subjected to denitration and desulfurization treatment through the denitration device 5 and the desulfurization device 6, it is released from the chimney 2 to the atmosphere. Therefore, when contacting the absorption liquid and the gas may be contacted with the purified gas after the desulfurization treatment, the absorption tower of the CO ₂ recovery unit to the duct 3 between the desulfurization device 6 and the chimney 2 It is proposed to intervene. However, when such an absorption tower is newly installed, there are problems such as securing a place for installing the absorption tower and requiring a considerable amount of equipment cost. The present invention has been made in view of such circumstances, and an object of the present invention is to provide a CO ₂ recovery apparatus capable of recovering CO ₂ while effectively utilizing existing facilities. . [0006] In order to achieve the above object, a CO ₂ recovery apparatus of the present invention denitrifies combustion exhaust gas discharged from a combustion apparatus with a denitration apparatus and desulfurizes with a desulfurization apparatus.
Later, the carbon dioxide in the flue gas is collected and
In a device for opening to the atmosphere, a plurality of
Providing several packed beds and above the top packed bed
Spraying an absorbent such as an alkanolamine solution
Install a laser nozzle to absorb carbon dioxide in exhaust gas
It is formed as an absorption tower, and a heater is installed in the chimney above the absorption tower.
And connecting an absorbent regeneration line to the bottom of the chimney
In both cases, the absorbent that has absorbed carbon dioxide
Knockout drum that partially separates carbon dioxide from the collected liquid
Connect the knockout drum's absorbing liquid
A regeneration tower that releases carbon dioxide in the absorbing solution is installed and
A reboil that extracts a portion of the absorbent in the live tower, raises the temperature, and returns
Connects La and Reclaimer and is regenerated and absorbed by its regeneration tower
The chimney at the top of the absorption tower
Collected by a CO ₂ storage facility through a heater installed in the
Supply the absorbent regenerated in the live tower to the spray nozzle
It is like that . A chimney is a structure that discharges exhaust gas from a high altitude into the atmosphere. A part of the chimney is formed as an absorption tower for removing CO ₂ in gas, and a function of recovering CO ₂ is provided. Was held. In other words, multi-stage packed layers are provided in the chimney,
Spray the absorbent such as an alkanolamine solution onto the
A laser nozzle is installed, and a part of the chimney is converted to an absorption tower.
Gas and liquid contact with the absorbent in the packed bed while the gas rises up the chimney.
And release it to the atmosphere after absorbing and removing CO ₂ in exhaust gas
It is to, CO ₂ times without having to build the absorption tower separately
I can do it. In addition, the absorption liquid from which CO ₂ has been removed
And reheat it with a reboiler and reclaimer.
To release CO ₂ from Osamueki, intake of CO ₂ that is its release
Flowed through the heater provided at the top of the collection tower and gas-liquid contacted with the absorption tower
White smoke can be prevented by heating the exhaust gas.
You. An embodiment of the present invention will be described below in detail with reference to the accompanying drawings. In FIG. 1, reference numeral 1 denotes a boiler as a combustion device. The boiler 1 burns fuel such as coal to generate steam supplied to a power generation steam turbine and the like. An exhaust gas duct 3 for guiding combustion exhaust gas to a chimney 2 is connected to the boiler 1.
An electric precipitator (EP) 4, for example, a denitration apparatus 5 for blowing NOx or the like into exhaust gas to remove NOx, and a desulfurization apparatus 6 for removing SOx by bringing exhaust gas after denitration into contact with, for example, a limestone slurry absorbent. Are provided in order. The exhaust gas duct 3 is connected to the lower part of the chimney 2, and the exhaust gas subjected to dust removal, denitration and desulfurization processing through the duct 3 rises in the chimney 2 and is opened to the atmosphere from the top of the chimney 2. . Above the duct connection portion in the chimney 2, a plurality (three stages in the illustrated example) of packing layers such as Raschig rings are provided, and above the filling layer 7, an MEA is provided in the chimney 2. A spray nozzle 8 for spraying an absorbing liquid such as a solution of an alkanolamine such as DEA, TEA or TEA is provided, and the absorbing liquid (for example, MEA solution (monoethanolamine solution)) sprayed from the spray nozzle 8 and the exhaust gas are mainly used. in contact countercurrent with a filling layer 7 to CO ₂ in the gas is adapted to be absorbed and removed in the absorption liquid, that part of the chimney 2 is formed as the absorption tower 10 of the CO ₂ recovery apparatus 9 Become. The absorbing liquid that has absorbed CO ₂ accumulates in the lower part of the chimney 2, and the bottom thereof is connected to an absorbing liquid regeneration line 11. The absorbent regeneration line 11 is connected to a knockout drum 14 via a filter 12 and a first heat exchanger 13. The knockout drum 14 separates gas (CO ₂ ) from the dust-absorbed and heated absorbent.
The separated CO ₂ is compressed by a CO ₂ compressor 15 and then led to a second accumulator 16 where the CO ₂ is removed.
_{2 It} is led to the storage facility 17. On the other hand, the absorbing liquid is supplied to the CO ₂ regeneration tower 20 through the second heat exchanger 19 by the first pump 18. [0013] regenerator 20 is for performing playback from the absorbing liquid that has absorbed CO ₂ absorption liquid to release CO _2, withdrawing a portion of the absorbent in the regenerator 20, the temperature of this solution given And a reclaimer 22 for removing impurities in the absorbing solution. These reboilers 2
1 and the reclaimer 22 use steam as a heat source, and the absorbing solution heated by the reboiler 21 and the reclaimer 22 is returned to the regenerator 20 so that the temperature in the regenerator 20 is controlled to a predetermined temperature. I have. Specifically, when the absorbing solution is the MEA solution, the temperature in the regeneration tower 20 is about 110 to
The temperature of the absorbing solution is raised by the reboiler 21 and the reclaimer 22 so as to reach 120 ° C. This is because if the temperature of the absorbing solution is about 110 to 120 ° C., CO ₂ is released from the absorbing solution (MEA solution) to regenerate the absorbing solution. The released CO ₂ is used as a heat source of a heater 23 provided above the spray nozzle 8 in the chimney 2. The heater 23 converts the exhaust gas to a predetermined temperature, for example, 80 ° C.
The temperature is raised to prevent white smoke. Then, after the CO ₂ is cooled from the heater 23 via the heat exchanger 24, it is sent to the first accumulator 25, and a part of the CO 2 is
_{2 While being} stored in the storage facility 17, the remaining
And is returned to the regeneration tower 20 via the An absorbent line 27 for supplying a regenerated absorbent (absorbed CO ₂ released) to the spray nozzle 8 is connected to the bottom of the regenerator 20. The second heat exchanger 19, the first heat exchanger 1
3, the heat exchanger 28 and the second pump 29 are sequentially provided,
The absorbing liquid cooled to about 50 to 60 ° C. is supplied to the spray nozzle 8 through the heat exchangers 19, 13, and 28. Next, the operation of this embodiment will be described. The high-temperature combustion exhaust gas from the boiler 1 is firstly subjected to dedusting treatment by an electric dust collector 4 and then denitrification and desulfurization treatment through a denitration device 5 and a desulfurization device 6. The gas after the desulfurization treatment is led to the chimney 2 at a temperature of about 48 to 50 ° C., and rises in the chimney 2. During this rise, the absorption liquid sprayed from the spray nozzle 8 (MEA solution _{(monoethanolamine; OH · CH 2 · CH 2} · NH 2)) and in contact countercurrent with a filling layer 7 or the like, CO in the gas ₂ is absorbed and removed by the absorbing solution. The reaction that occurs when this MEA solution absorbs CO ₂ is expressed as follows. 2RNH ₂ + CO ₂ + H ₂ O → (RNH ₃ ) ₂ CO ₃ (RNH ₃ ) ₂ CO ₃ + CO ₂ + H ₂ O → 2RNH ₃ H
The gas from which CO ₃ 2RNH ₂ + CO ₂ → RNHCOONH ₃ R CO ₂ has been removed is passed through a heater 23 to about 80 ° C.
After the temperature of the chimney 2 is increased, the air is released from the top of the chimney 2 to the atmosphere.
At this time, since the temperature is raised to about 80 ° C. by the heater 23, white smoke is not generated. The absorbing solution having absorbed CO ₂ flows down the chimney 2, flows into the absorbing solution regenerating line 11 from the bottom, passes through the filter 12 and the first heat exchanger 13, and further passes through the knockout drum 14. After the (CO ₂ ) is separated, it is led to the CO ₂ regeneration tower 20 via the second heat exchanger 19. In the regeneration tower 20, a part of the absorption liquid is withdrawn, heated by a reboiler 21 and a reclaimer 22, and then returned to the regeneration tower 20, where the temperature in the regeneration tower 20 is reduced to about
Maintained at 110-120 ° C. Thereby, the absorption liquid (M
EA solution) releases CO ₂ to regenerate the absorbing solution. After the CO ₂ contributes to the temperature rise of the exhaust gas, it is led to the first accumulator 25 via the heat exchanger 24,
A part is returned to the regeneration tower 20 via the pump 26, and the remainder is sent to the CO ₂ storage facility 17 and stored there. Its CO ₂ storage facilities 17, separated in the knock-out drum 14, CO ₂ via the CO ₂ compressor 15 and the second accumulator 16 is guided. The regenerated absorbing solution (absorbing solution releasing CO ₂ ) is cooled to about 50 to 60 ° C. through the second heat exchanger 19, the first heat exchanger 13, and the heat exchanger 28. Is supplied to the spray nozzle 8 again by the second pump 29 so as to contribute to the recovery of CO ₂ . As described above, since a part of the chimney 2 is formed as the absorption tower 10 of the CO ₂ recovery device 9, the exhaust gas comes into gas-liquid contact with the absorbing liquid while passing through the chimney 2, and the CO _{2 in} the gas is removed. Is released to the atmosphere after absorption and removal, so that there is no need to separately construct the absorption tower 10 of the CO ₂ recovery device 9. That is, the chimney 2 is a structure that discharges purified exhaust gas such as denitration and desulfurization treatment from the high altitude to the atmosphere.
Is formed as an absorption tower 10 for removing CO ₂ in the gas, that is, a part of the chimney 2 is diverted to the absorption tower 10,
By providing the ability to collect the _2, without building a CO ₂ absorption tower separately, thereby the recovery of CO _2. Therefore,
There is no problem with the place to install the absorption tower, the cost of building the absorption tower can be reduced, and the equipment cost can be prevented from rising.The decarbonation process can be used as an exhaust gas treatment process while effectively using the existing equipment. Can be incorporated. In summary, according to the present invention, in the chimney,
Multi-stage packed layers are provided, and alkanolamine
Provide a spray nozzle for spraying absorbing liquid such as liquid
Constructing an absorption tower separately by diverting part of it to an absorption tower
CO ₂ can be recovered without the need . Also absorbs and removes CO ₂
The absorbed liquid is introduced into the regeneration tower, and reboiler and reclaimer
By raising the temperature, CO ₂ is released from the absorbing solution ,
The emitted CO ₂ flows into a heater provided at the top of the absorption tower to absorb it.
Prevents white smoke by heating exhaust gas in gas-liquid contact at the collection tower
Can be stopped.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing one embodiment of the present invention. FIG. 2 is a configuration diagram illustrating an example of a conventional exhaust gas treatment process. [Description of Signs] 1 Combustion device (boiler) 2 Chimney 10 Absorption tower

Continuation of front page (56) References JP-A-3-193116 (JP, A) JP-A-4-271809 (JP, A) JP-A-5-245339 (JP, A) JP-A-50-19034 (JP) JP-A-51-102233 (JP, A) JP-A-52-65174 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) B01D 53/34

Claims (1)

(57) [Claims] [Claim 1] Decompose combustion exhaust gas discharged from a combustion device.
After denitrification with a nitrification device and desulfurization with a desulfurization device, the combustion exhaust gas
The carbon dioxide in the gas and release it to the atmosphere from the chimney.
In the apparatus, a plurality of packed beds are provided in the chimney.
And at the top of the top packed bed
Spray nozzle for spraying absorbing solution such as amine solution
As an absorption tower to absorb carbon dioxide in exhaust gas
A heater is provided in the chimney above the absorption tower,
Connect the absorbent regeneration line to the bottom
In the raw line, part of the diacid
Connect a knockout drum to separate carbonized
Introduce the absorption liquid in the
A regeneration tower that emits carbon is provided, and the absorption liquid in the regeneration tower is
Reboiler and reclaimer to extract a part, raise the temperature and return
Connected, regenerated in the regeneration tower and released from the absorbent
A heater provided with a carbon dioxide in a chimney above the absorption tower
Through the CO ₂ storage facility and regenerated by the regeneration tower.
A carbon dioxide recovery device , wherein a collected liquid is supplied to the spray nozzle .