JP3426685B2 - Method for removing carbon dioxide in flue gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [0001] BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention is contained in flue gas.
CO_Two(Carbon dioxide) removal method
Or, a specific amino acid metal salt and a specific amine compound
Using the mixed aqueous solution, CO in the exhaust gas at atmospheric pressure_Two
And a method for removing the same. [0002] 2. Description of the Related Art In recent years, one of the causes of the global warming phenomenon is
And CO_TwoPoint out greenhouse effect and protect global environment
Internationally, measures have been urgently needed for this. CO_Two
Sources of fossil fuels are any human
Demands for emission control are becoming stronger
Tend to be. Fire using large amounts of fossil fuels
Boiler emissions from power generation facilities such as power plants.
The gas is brought into contact with an alkanolamine aqueous solution, etc.
CO in gas_TwoMethod for removing and recovering and recovered
CO_TwoEnergy storage method without releasing to the atmosphere
Has been studied. As alkanolamines, monoethanol
Luamine, diethanolamine, triethanolamine
, Methyldiethanolamine, diisopropanolamine
Min, diglycolamine, etc.
However, monoethanolamine (MEA) is usually preferred
Can be However, the above-mentioned algorithm represented by MEA
CO2 in combustion exhaust gas with aqueous solution of canolamine_TwoAbsorbs
Even when used as an absorbent to remove
CO per predetermined amount of liquid_TwoAbsorption amount, amine of predetermined concentration
CO per unit mole of amine in aqueous solution_TwoAbsorption amount, specified concentration
CO in degrees_TwoAbsorption rate, and after absorption
The thermal energy required to regenerate the aqueous
Therefore, it is not always satisfactory. By the way, amine compounds are prepared from various mixed gases.
There are many known techniques for separating acid gas using
You. JP-A-53-100180 discloses that (1)
A partial carbon atom or a tertiary carbon atom
At least one secondary amino attached to either of the offspring
Group or a primary amino group attached to a tertiary carbon atom.
At least 50 mol% of the sterically hindered amine
An amino acid comprising at least about 10 mol% of a mino alcohol
Physical adsorbent for gas mixtures and (2) acidic gases
Amine-solvent liquid comprising a solvent for the amine mixture
Consisting of contacting the gaseous mixture with the absorbent
A method for removing acid gases is described. With sterically hindered amines
Is 2-piperidineethanol, ie, [2- (2
-Hydroxyethyl) -piperidine] and 3-amino-
3-methyl-1-butanol and the like are tertiary amino alcohols
As 3-dimethylamino-1-propanol
However, if the solvent contains water up to 25% by weight,
Good sulfoxide compounds, etc.
In this publication, high concentrations of carbon dioxide and hydrogen sulfide,
35% CO_TwoAnd 10-12% H_TwoThrough with S
A gaseous mixture is illustrated, and in the examples CO 2_TwoSo
Are used. Japanese Patent Application Laid-Open No. 61-71819 discloses a three-dimensional
Acidic gases containing non-aqueous solvents such as hindered amines and sulfolane
A composition for scrapping is described. Steric hindrance
2-amino-2-methyl as the primary monoamino alcohol
L-1-propanol (AMP) and the like, and
Used. In the embodiment, the gas to be processed is
CO_TwoAnd nitrogen, CO_TwoAnd helium are used. Ma
Also, an aqueous solution of amine and potassium carbonate is used as an absorbent.
Have been used. It also describes the use of water
You. Further, in this publication, CO_TwoSteric hindrance to absorption of
The advantages of min are illustrated using a reaction equation. [0006] Chemical Engineering Science (C
chemical Engineering Science), Vol. 41, No. 4, 99
On pages 7 to 1003, the hindered amine 2-amino
No-2-methyl-1-propanol (AMP) aqueous solution
A carbon dioxide absorption behavior is disclosed. With the gas to be absorbed
And atmospheric pressure CO_TwoAnd CO_TwoAnd a mixture of nitrogen used
Have been. Chemical Engineering Science (C)
chemical Engineering Science), Vol. 41, No. 2, 40
On page 5-408, around room temperature, like AMP
Each water solution of hindered amine and linear amine such as MEA
Liquid CO_TwoAnd H_TwoAbsorption rate for S is reported
You. According to this, CO_TwoWhen the partial pressure of
There is no significant difference between the two at a liquid concentration of 0.1 to 0.3M. But,
Using an aqueous solution having a concentration of 0.1 M,_TwoWhen the partial pressure is 1, 0.
5. When reduced to 0.05 atm, 0.05 atm
Indicates that AMP has a much lower absorption rate than MEA
You. [0008] US Patent 3,622,267 describes
Is methyldiethanolamine and monoethylmonoethanol
Using an aqueous mixture containing nolamine, such as crude oil
High partial pressure C contained in synthesis gas such as partial oxidation gas
O_TwoFor example, 40 atm of 30% CO _TwoElaborate the synthesis gas
The technology for manufacturing is disclosed. German Offenlegungsschrift 1,542,415
Contains CO_Two, H_TwoTo improve the absorption speed of S and COS
Physical or chemical monoalkyl alkanolamine
A technique for adding to an absorbent is disclosed. Germany as well
Published Japanese Patent No. 1,904,428 discloses that
Tanolamine absorbs methyldiethanolamine
There is disclosed a technique which is added for the purpose of improving the content. US Pat. No. 4,336,233 describes
Uses pipetting for the purification of natural gas, syngas and gasified coal gas.
0.81-1.3 mol / l aqueous solution of azine washed
Piperazine as methyldiethanolamide
, Triethanolamine, diethanolamine, mono
Washing with an aqueous solution together with a solvent such as methylethanolamine
Techniques for use as liquids are disclosed. [0011] Similarly, Japanese Patent Laid-Open No. 52-63171 discloses
Is tertiary alkanolamine, monoalkylalkano
Piperazine or hydroxyethyl
Piperazine derivatives such as perazine were added as accelerators
CO_TwoAn absorbent is disclosed. Apart from these,
The amino acid metal salt represented by the general formula [1] used in the present invention
Aqueous solution of CO_TwoUsed for collection or
Is CO_TwoAnd H_TwoH from synthetic gas containing S_TwoS only
The technology used to selectively recover
You. [0012] As described above, the combustion exhaust gas
To CO_TwoThere is a need for a method for removing
You. In particular, a constant concentration of CO_TwoCombustion with aqueous solution containing absorbent
When treating exhaust gas, CO per mole of absorbent_Two
Absorbed amount, CO per unit volume of aqueous solution_TwoAbsorption amount and
It is important for the time being to select an absorbent with a high absorption rate
It is an issue. And CO_TwoAfter absorption of CO_TwoSeparate
Low absorption of heat energy required to regenerate absorbent
Agents are desired. Especially CO_TwoHas a large absorption capacity
Nevertheless, improve the absorption rate of absorbent with low absorption rate
It is desired. [0013] Means for Solving the Problems The present inventors have solved the above problems.
In view of, CO in combustion exhaust gas_TwoUsed in removing
After a thorough study of the absorbent, a specific amino acid metal
Use a relatively small amount of a specific amine compound in a salt
In order to improve the absorption rate of amino acid metal salts,
It has been found that the present invention is particularly effective, and
I was able to. That is, the present invention provides a method for preparing dimethylaminoacetic acid
100 parts by weight of lithium (X) and piperazine (Y) 110
Parts by weight of the mixed aqueous solution and flue gas at atmospheric pressure
And the CO in the flue gas_TwoHow to remove
You. [0015] The function used in the present inventionRuaMetallic acid of amino acidHajiMethyl
Potassium aminoacetate(X) dimethylaminoacetic acid
Used together with potassium (X) is piperazine (Y)
It is. Potassium dimethylaminoacetate (X) and pipette
Mixing ratio of azine (Y) is potassium dimethylaminoacetate
(X) 100 parts by weight of piperazine (Y)Is 1~ 1
The range is 0 parts by weight. CO in combustion exhaust gas_TwoAbsorbent liquid
Potassium dimethylaminoacetate (X)
Mixed aqueous solution of perazine (Y) (hereinafter also referred to as "absorbent")
The concentration of potassium dimethylaminoacetate (X) in
It is always 15 to 65% by weight. Also, contact with flue gas
The temperature of the mixed aqueous solution is usually in the range of 30 to 70 ° C.
You. In the mixed aqueous solution used in the present invention, if necessary,
Corrosion inhibitors and the like are added. Further, in the present invention,
Atmospheric pressure acts as a blower to supply combustion exhaust gas
Pressure range near atmospheric pressure that is
You. [0017] CO in the flue gas of the present invention_TwoRemove
The process that can be adopted by the method is not particularly limited, but
An example will be described with reference to FIG. Figure 1 shows the main components
Only the equipment is shown and the attached equipment is omitted. In FIG. 1, 1 is
CO removal_TwoColumn 2, lower filling section, 3 upper filling section or tower
Ray 4 is de-CO_TwoTower flue gas supply port, 5 de-CO2_Two
Combustion exhaust gas outlet, 6 is an absorbent supply port, 7 is a nozzle, 8
Is a flue gas cooler provided as required, and 9 is a
10, a filling section, 11 a humidifying cooling water circulation pump, 12
Is a makeup water supply line, 13 is CO_TwoAbsorbed liquid drained
Outlet pump, 14 is a heat exchanger, 15 is absorption liquid regeneration (hereinafter, referred to as
Tower, 16 for nozzle, 17 for bottom filling
Part, 18 is regenerative heater (reboiler), 19 is top filling
Part, 20 is a reflux water pump, 21 is CO_TwoThe separator, 22
Captured CO_TwoA discharge line, 23 is a regenerator reflux condenser, 24
Is a nozzle, 25 is a regeneration tower reflux water supply line, and 26 is combustion
Exhaust gas supply blower, 27 is a cooler, 28 is recirculation tower reflux water
It is a supply port. In FIG. 1, the combustion exhaust gas is supplied to the combustion exhaust gas.
It is pushed into the flue gas cooler 8 by the supply blower 26,
The humidified cooling water from the nozzle 9 comes into contact with the filling section 10 to humidify
Cooled and de-CO_TwoDe-C through tower flue gas supply port 4
O_TwoGuided to tower 1. Humidifying cooling water in contact with flue gas
Accumulates in the lower part of the flue gas cooler 8 and is pumped by the pump 11.
It is circulated to the nozzle 9. Humidifying cooling water generates combustion exhaust gas.
The water is gradually lost by humidification and cooling.
It is replenished by the supply line 12. Humidification and cooling of combustion exhaust gas
For further cooling from the state of, humidification cooling circulation pump
Place the heat exchanger between 11 and nozzle 9 and humidify the cooling water
It is possible by cooling and supplying to the flue gas cooler 8
Becomes DeCO2_TwoCombustion exhaust gas pushed into tower 1
Is a constant concentration of the absorbing liquid supplied from the nozzle 7 and the filling section 2
In countercurrent contact with CO_TwoIs the absorption liquid
More absorbed and removed_TwoThe combustion exhaust gas is in the upper filling section 3
Go to. CO removal_TwoThe absorption liquid supplied to the column 1 is CO_TwoTo
Absorbed, and due to the heat of reaction due to the absorption, usually
Higher than the temperature at which_TwoAbsorbed liquid absorbed
The heat is sent to the heat exchanger 14 by the discharge pump 13 and heated.
It is led to the absorbent regeneration tower 5. Temperature control of regenerated absorbent
The knot is connected to the heat exchanger 14 or, if necessary, the heat exchanger 14.
This is performed by a cooler 27 provided between the absorption liquid supply ports 6.
be able to. In the regeneration tower 15, heating by the regeneration heater 18 is performed.
The absorption liquid is regenerated in the lower filling section 17 by heat, and the heat exchanger
14 to remove CO_TwoReturned to Tower 1. Absorbent
In the upper part of the raw tower 15, CO separated from the absorbing solution_Two
Comes into contact with the reflux water supplied from the nozzle 24 and returns to the regeneration tower.
Cooled by the flow cooler 23,_TwoC at the separator 21
O_TwoThe water vapor accompanying the water is separated from the condensed reflux water,
Income CO_TwoCO from the discharge line 22_TwoGuided to the recovery process
You. Part of the reflux water is returned to the regeneration tower 15 by the reflux water pump 20
And partly degassed through the recycle tower reflux water supply line 25.
O_TwoIt is supplied to the regeneration tower reflux water supply port 28 of the tower 1. this
The reflux water in the regeneration tower contains a small amount of absorbing solution.
CO_TwoIt comes into contact with the exhaust gas at the upper filling section 3 of the tower 1 and
Traces of CO contained in_TwoContributes to the removal of. [0021] The present invention will be described below in detail with reference to examples.
You.(Examples 1-2, Comparative Examples 1-3, Reference Examples 1-3) Amino acid metal in a glass reaction vessel installed in a thermostatsalt
WhenPotassium dimethylaminoacetate orIt is a reference example
Potassium α-methylaminopropionate and piperazine
Was mixed at a concentration shown in Table 1 with 50 ml of an aqueous solution.
And agitate the test gas at 40 ° C for 1 l under atmospheric pressure.
Torr / min flow rate. Test gas is CO_Two10 mol
%, O_Two3 mol%, N_Two40 having a composition of 87 mol%
C. model combustion exhaust gas (equivalent to LNG firing) was used. Trial
Test gas and keep the CO_TwoConcentration is equal
At the point when the CO_TwoTo CO_TwoAnalyzer
(Total organic carbon meter)_TwoSaturated absorption
(Nm^ThreeCO_Two/ M^ThreeSolution, molar CO_Two/ Mol amino acid
Metal salt). Also discharged from the glass reactor
Gas composition is continuously measured with a gas analyzer and included
First CO_TwoConcentration (initial outlet gas CO_TwoConcentration) and
CO_TwoWas determined (initial absorption rate). As is clear from the results in Table 1, the present invention
ThanPotassium dimethylaminoacetate(X) piperazine
By using a relatively small amount of (Y),Dimethi
Potassium laminoacetateThan when (X) is used alone
Initial outlet gas CO_TwoConcentration is significantly lower, absorbing
It can be seen that a significant increase in speed has been achieved.reference
As you can see from the comparison with the exampleThis is especially dimethylamino
Notable when a small amount of piperazine was used in potassium acetate.
You. Piperazine to potassium dimethylaminoacetate
The time required for 90% saturation is very short when used in small quantities
This is reflected in the shrinkage. Table 1 shows the comparison
Therefore, the results when piperazine and MEA were used alone were
Indicated. [0023] [Table 1] [0024](Example 3, Comparative example 4) Further investigation of the heat energy required to regenerate the absorbent
Example 1 and Comparative Example3Liquid (concentration 3)
0 wt%) and CO_TwoHeat of reaction (absorption heating value)
Was. Put 200 g of absorbing liquid into an adiabatic tester,
Stir with a stirrer and leave until the temperature of the solution stabilizes.
Was. Next, pure CO_TwoIn the tester at a speed of 200 cc / min
And CO at the inlet and outlet of the tester_TwoFlow rate, absorbing liquid
Was continuously recorded. CO at tester outlet_TwoFlow rate
The test was terminated at the time of the rapid increase. CO absorbed in the absorbing solution_TwoNumber of moles (mol
Load), CO_TwoFrom the temperature rise from the start of
Is CO_TwoCalorie (Kcal /
Mol) absorbed CO_TwoWas calculated for each mole interval. The test
The heat capacity of the device is as follows.
Energize the heater at 0.3A for a predetermined time and calculate from the temperature rise
Was. In addition, the temperature range of the test is 20 to 80 ° C, and the chamber at the time of measurement.
The temperature was between 20 and 25C. Table 2 shows the results. [0026] [Table 2] As can be seen from Table 2, the mixed compound used in the present invention and C
O_TwoHeat of reaction with is smaller than that of MEA.
Energy required for regeneration is significantly smaller than that of MEA
It turns out that it is very advantageous. [0027] As described in detail above, the method of the present invention
To flue gas under atmospheric pressurePotassium dimethylaminoacetate
UmmThe mixed aqueous solution of (X) and piperazine (Y) was used as the absorbing solution.
By usingPotassium dimethylaminoacetate
(X) is more CO2 than when used alone._TwoOf the absorption rate
An improvement is achieved in points. Also, when using MEA
In terms of renewable energy, CO_TwoEfficiently removed
It was coming.

[Brief description of the drawings] FIG. 1 is a diagram illustrating an example of a process that can be employed in the present invention.

──────────────────────────────────────────────────続 き Continuation of the front page (72) Shigeru Shimojo 3-3-22 Nakanoshima, Kita-ku, Osaka City, Osaka Prefecture Inside Kansai Electric Power Company (72) Inventor Masaki Iijima 2-5-1 Marunouchi, Chiyoda-ku, Tokyo Mitsubishi Heavy Industries, Ltd. Headquarters (72) Inventor Kaoru Mitsuoka 4-2-2 Kannon Shinmachi, Nishi-ku, Hiroshima-shi, Hiroshima Mitsubishi Heavy Industries, Ltd. Hiroshima Laboratory (56) References JP-A-52-63171 (JP, A) JP-A-52-154991 (JP, A) JP-A-59-73415 (JP, A) JP-A-5-184865 (JP, A) JP-A-5-301024 (JP, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B01D 53/34

Claims (1)

(57) [Claim 1] Potassium dimethylaminoacetate (X) 10
0 parts by weight of piperazine (Y). 1 to a method for removing CO ₂ in the combustion exhaust gas comprising contacting a mixed aqueous solution of 10 parts by weight and the combustion exhaust gas under atmospheric pressure.