Carbon dioxide trapping device and method capable of producing electricity

Abstract

An apparatus and process are provided for electricity production and high-efficiency trapping of carbon dioxide, using carbon dioxide within combustion exhaust gas and converging technologies associated with a carbon dioxide absorption tower and a generating device using ions which uses a difference in concentration of salinity between seawater and freshwater. It is expected that enhanced electrical energy production efficiency, an effect of reducing costs for the operation of a carbon dioxide trapping process, and electricity production from carbon dioxide, which is a greenhouse gas, can be simultaneously achieved by increasing the difference in concentration using an absorbent for absorbing carbon dioxide.

Claims

1. A carbon dioxide capturing apparatus capable of producing electricity, comprising: an absorption tower in which a gas including carbon dioxide comes in contact with an absorbent and is absorbed by the absorbent, the absorption tower comprising a flow path for discharging an absorption solution that has absorbed carbon dioxide; an electricity-generating device including: a space formed between a cation electrode and an anion electrode the space including a fluid solution flow path through which a fluid solution moves comprising a first flow path formed by a cation exchange membrane spaced apart from the cation electrode and a second flow path formed by an anion exchange membrane spaced apart from the anion electrode, and an absorption solution flow path connected to the flow path of the absorption tower between the first flow path and the second flow path to be supplied with the absorption solution that has absorbed carbon dioxide discharged from the absorption tower, a heat exchanger in which the absorption solution that has absorbed carbon dioxide discharged from the absorption tower and a regenerated absorption solution passing through the electricity-generating device are heat-exchanged; a first liquid transfer pump for supplying the absorption solution that has absorbed carbon dioxide discharged from the absorption tower through the heat exchanger to the absorption solution flow path; and a second liquid transfer pump for supplying the regenerated absorption solution passing through the electricity-generating device through the heat exchanger to the absorption tower; wherein the cation exchange membrane is a membrane that allows only cations to selectively pass through, and the anion exchange membrane is a membrane that allows only anions to selectively pass through, and wherein when the absorption solution has a relatively higher concentration than the fluid solution or the absorption solution has a relatively lower concentration than the fluid solution, the absorption solution is supplied from the absorption tower to the absorption solution flow path of the electricity-generating device and the fluid solution is supplied to the fluid solution flow path, such that a cation passes through the cation exchange membrane and an anion passes through the anion exchange membrane due to the difference in concentration between the fluid solution and the absorption solution having absorbed carbon dioxide, so that electricity is generated by a potential difference by moving cations and anions at the electricity-generating device.

2. The carbon dioxide capturing apparatus capable of producing electricity according to claim 1, wherein the absorbent includes, as a solute, one or more selected from an aqueous electrolyte group consisting of amines, alkali metal bicarbonates, alkali carbonates, carbonates, hydroxides, borates, phosphates, nitrates, acids, and sodium chloride and an organic electrolyte group consisting of propylene carbonate (PC), diethyl carbonate (DEC), and tetrahydrofuran (THF).

3. The carbon dioxide capturing apparatus capable of producing electricity according to claim 1, wherein the absorbent further includes, as an additive, a corrosion inhibitor, a coagulant aid, an antioxidant, an oxygen scavenger, an antifoaming agent, or a combination thereof.

4. The carbon dioxide capturing apparatus capable of producing electricity according to claim 1, wherein the absorbent includes, as a solvent, one or more materials selected from the group consisting of an aqueous solvent group and an organic solvent group, wherein the aqueous solvent group includes a solvent selected from the group consisting of pure water, freshwater, brackish water, saline water, and a mixed solvent of an alcohol and water, and wherein the organic solvent group includes an aliphatic hydrocarbon group consisting of hexane; an aromatic hydrocarbon group consisting of benzene, toluene, xylene, and methylnaphthalene; a heterocyclic compound group consisting of quinoline and pyridine; a ketone group consisting of acetone, methyl ethyl ketone, and cyclohexanone; an ester group consisting of methyl acetate and methyl acrylate; an amine group consisting of diethylenetriamine and N,N-dimethylaminopropylamine; an ether group consisting of diethyl ether, propylene oxide, and tetrahydrofuran (THF); an amide group consisting of N-methylpyrrolidone (NMP), dimethylformamide, and dimethylacetamide; and a polar aprotic solvent group consisting of hexamethylphosphoramide and dimethyl sulfoxide.

5. The carbon dioxide capturing apparatus capable of producing electricity according to claim 1, wherein the absorption solution that has absorbed carbon dioxide, which is supplied to the absorption solution flow path, and the fluid solution supplied to the first flow path and the second flow path are supplied alternately.

6. The carbon dioxide capturing apparatus capable of producing electricity according to claim 1, wherein the absorption solution that has absorbed carbon dioxide and the fluid solution are supplied in parallel.

Description

DESCRIPTION OF DRAWINGS

(1) FIG. 1 is a configuration diagram of a carbon dioxide capturing apparatus capable of producing electricity according to the present invention.

(2) FIG. 2 is a conceptual diagram of a carbon dioxide capturing apparatus capable of producing electricity according to the present invention.

(3) FIG. 3 is a configuration diagram of a carbon dioxide capturing apparatus capable of producing electricity, which includes a heat exchanger, according to the present invention.

(4) FIG. 4 shows results of power density and closed circuit voltage according to Embodiment 1.

(5) FIG. 5 shows results of a change in pH of an absorption solution and a fluid solution according to Embodiment 1.

(6) FIG. 6 shows results of changes in maximum energy, power density, closed circuit voltage, and pH according to Embodiment 2.

MODES OF THE INVENTION

(7) Hereinafter, the exemplary embodiments of the present invention will be described with reference to the appended drawings. It should be noted that it is possible for the same components to have the same reference numerals even if they are shown in different drawings. Detailed descriptions of known functions and configurations determined to unnecessarily obscure the gist of the invention will be omitted.

(8) The present invention is largely configured of two parts, an absorption tower in which carbon dioxide is selectively absorbed and an electricity-generating device using ion in which electricity is produced due to a difference in concentration between an absorption solution and a fluid solution, and a configuration diagram of this is shown in FIG. 1.

(9) In addition, the present invention is largely configured of three parts, an absorption tower in which carbon dioxide is selectively absorbed, a heat exchanger in which heat is exchanged between an absorption solution that has absorbed carbon dioxide and a regenerated absorption solution passing through the electricity-generating device using ion, and the electricity-generating device using ion in which electricity is produced due to a difference in concentration between the absorption solution and a fluid solution, and a configuration diagram of this is shown in FIG. 3. Components of the present invention will now be described.

(10) First, an absorption tower 1 will be described. The absorption tower according to the present invention is a device in which carbon dioxide from an exhaust gas 2 containing carbon dioxide is absorbed through contact, and is configured such that an absorption solution is supplied to an upper part of the absorption tower, and the absorption solution 4 that has absorbed carbon dioxide is transferred from a lower part of the absorption tower to a heat exchanger 5. The absorption tower may include a filler, and the absorption solution that has absorbed carbon dioxide may be transferred to the heat exchanger by a liquid transfer pump.

(11) In the heat exchanger 5, heat is exchanged between the absorption solution that has absorbed carbon dioxide and a regenerated absorption solution passing through the electricity-generating device using ion. A fluid flowing into the heat exchanger is supplied in counter-flow or parallel-flow directions.

(12) In the electricity-generating device using ion, as shown in FIG. 1, a space formed between a cation electrode 7c and an anion electrode 7d is divided by a cation exchange membrane 7a and an anion exchange membrane 7b. That is, the electricity-generating device using ion 7 is composed of a first flow path 7f between the cation exchange membrane 7a and the cation electrode 7c, a second flow path 7g between the anion exchange membrane 7b and the anion electrode 7d, and an absorption solution flow path 7e between the cation exchange membrane 7a and the anion exchange membrane 7b.

(13) A fluid solution flows in the fluid solution flow path including the first flow path 7f and the second flow path 7g, and the absorption solution that has absorbed carbon dioxide flows in the absorption solution flow path 7e.

(14) The cation exchange membrane 7a is a dense membrane that blocks the flow of an absorption solution and allows only cations to selectively pass through, and the anion exchange membrane 7b is a dense membrane that blocks the flow of an absorption solution and allows only anions to selectively pass through.

(15) The fluid solution may include an aqueous electrolyte such as NaCl, H.sub.2SO.sub.4, HCl, NaOH, KOH, NaNO.sub.3, and the like and an organic electrolyte such as propylene carbonate (PC), diethyl carbonate (DEC), or tetrahydrofuran (THF).

(16) In particular, one or more solvents selected from among aqueous solvents such as pure water, freshwater, brackish water, saline water, or a mixed solvent of an alcohol and water, and organic solvents including aliphatic hydrocarbons such as hexane and the like; aromatic hydrocarbons such as benzene, toluene, xylene, methylnaphthalene and the like; heterocyclic compounds such as quinoline, pyridine and the like; ketones such as acetone, methyl ethyl ketone, cyclohexanone and the like; esters such as methyl acetate, methyl acrylate and the like; amines such as diethylenetriamine, N,N-dimethylaminopropylamine and the like; ethers such as diethyl ether, propylene oxide, tetrahydrofuran (THF) and the like; amides such as N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide and the like; and polar aprotic solvents such as hexamethylphosphoramide, dimethyl sulfoxide and the like may be used as the fluid solution.

(17) Also, the absorption solution may move along the absorption solution flow path 7e, and the absorbent may include one or more selected from among aqueous electrolytes such as amines, alkali metal bicarbonates, alkali carbonates, carbonates, hydroxides, borates, phosphates, nitrates, acids, and sodium chloride and organic electrolytes such as propylene carbonate (PC), diethyl carbonate (DEC), and tetrahydrofuran (THF).

(18) The amines may be primary amines, secondary amines, or ammonia. The amines may be liquid or solid at room temperature and atmospheric pressure, or may be gases with vapor pressure or in a mist-phase. Primary amines may be saturated aliphatic primary amines such as methylamine, ethylamine, isopropylamine, propylamine, butylamine, 2-aminoethanol and the like, unsaturated aliphatic primary amines such as allylamine and the like, alicyclic primary amines such as cyclopropylamine and the like, and aromatic primary amines such as aniline and the like. Secondary amines may be saturated aliphatic secondary amines such as dimethylamine, diethylamine, diisopropylamine and the like, unsaturated aliphatic secondary amines such as diallylamine and the like, and aromatic secondary amines such as methylaniline and the like.

(19) Also, the amines may be ethyleneamine, ethanolamine (MEA), NN-butylethanolamine (BEA), ethylenediamine (EDA), diethanolamine (DEA), diisopropanolamine (DIPA), N-methyldiethanolamine (MDEA), diglycolamine (DGA), triethanolamine (TEA), o-methylhydroxylamine, ethanimidamine, N-(2-hydroxyethyl)ethylenediamine (AEEA), diethanoltriamine (DETA), N,N-dimethylethlethanolamine (DMMEA), 2-4n diisopropanolamine or 2n methyldiethanolamine (ADIP), piperidine, piperazine, morpholine, pyrrolidine, 2,2,6,6-tetramethyl-4-piperidinol (TMP), 2-amino-2-methylpropanol (AMP), 1-amino-2-propanol (MIPA), 2-methylaminoethanol (MMEA), 3-amino-1-propanol (MPA), diethylaminoethanol (DEMEA), 2-diisopropylaminoethanol (DIPMEA), 2-diethylaminoethanol (DEAE), 2-(diisopropylamino)ethanol (DIPAE), 2-(dimethylamino)-2-methylpropanol (DMAMP), N-ethyldiethanolamine (EDEA), N-isopropyldiethanolamine (IPDEA), N-tert-butyldiethanolamine (tBDEA), 1-(2-hydroxyethyl)pyrrolidine (HEP), 1-(2-hydroxyethyl)piperidine (HEPD), 1-methyl-2-piperidineethanol (1M-2PPE), 1-ethyl-3-hydroxypiperidine (1E-3HPP), 2-{[2-(dimethylamino)ethyl]methylamino}ethanol (DMAEMAE), N,N,N,N-tetrakis(2-hydroxyethyl)ethylenediamine (TKHEEDA), 2-[2-(dimethylamino)ethoxy]ethanol (DMAEE), bis[2-(N,N-dimethylamino)ethyl]ether (DAEE), 1,4-dimethylpiperazine (DMPZ), N,N,N,N,N-pentamethyldiethylenetriamine (PMDETA), N-methyl-N,N-bis[3-(dimethylamino)propyl]amine (PMDPTA), n-butyl di ethanol amine (BDEA), triisopropanolamine (TIPA), 4-(2-hydroxyethyl)morpholine (HEM), hydroxyisopropylmorpholine(N-(2-hydroxypropyl)morpholine) (HIPM), (2-(dibutylamino)ethanol (2-DBAE), 2,2-bis(hydroxymethyl)-2,22-nitrilotriethanol (HMNTE), N-methyl-4-piperidinol (MP), hexamethylenetetramine (HMTA), N,N-dicyclohexylmethylamine (DCHMA) and the like.

(20) In addition, the amines may be the sterically hindered amines KS-1, KS-2, and KS-3. Also, sterically hindered cyclic amines may include 1-amino-4-methylpiperazine, 1-(2-aminoethyl)-4-methylpiperazine, 1-(2-hydroxyethyl)-4-methylpiperazine, 1-(2-aminoethyl)piperazine, 1-(2-hydroxyethyl)piperazine, 2-aminoethylpiperazine, 1-ethylpiperazine, 2,5-dimethylpiperazine, cis-2,6-dimethylpiperazine, 1,4-dimethylpiperazine, trans-2,5-dimethylpiperazine, 1-methylpiperazine, 2-methylpiperazine, 1-ethylpiperazine, 2-piperidineethanol, 3-piperidineethanol, 4-piperidineethanol, 2-aminoethyl-1-piperidine, homopiperazine, and the like.

(21) The alkali carbonates may include potassium carbonate (K.sub.2CO.sub.3), sodium carbonate (Na.sub.2CO.sub.3), sodium hydroxide (NaOH), potassium hydroxide (KOH), potassium bicarbonate (KHCO.sub.3), sodium bicarbonate (NaHCO.sub.3), and the like. Also, the alkali carbonates may include compounds from the Benfield process developed by Union Carbide Corporation, the HIPure process known as the improved Benfield process, the Catacarb process developed by A. G. Eickmeyer, FLEXSORB HP developed by Exxon mobil Corporation, etc.

(22) In addition, the nitrate may be sodium nitrate (NaNO.sub.3). Also, the acid may be sulfuric acid (H.sub.2SO.sub.4) or hydrochloric acid (HCl).

(23) In particular, the absorption solution may also include aqueous electrolytes such as NaCl, H.sub.2SO.sub.4, HCl, NaOH, KOH, NaNO.sub.3, and the like, and organic electrolytes such as propylene carbonate (PC), diethyl carbonate (DEC), and tetrahydrofuran (THF), which is similar to the fluid solution.

(24) Particularly, one or more solvents selected from among aqueous solvents such as pure water, freshwater, brackish water, saline water, or a mixed solvent of an alcohol and water, or organic solvents including as aliphatic hydrocarbons such as hexane and the like; aromatic hydrocarbons such as benzene, toluene, xylene, methylnaphthalene and the like; heterocyclic compounds such as quinoline, pyridine and the like; ketones such as acetone, methyl ethyl ketone, cyclohexanone and the like; esters such as methyl acetate, methyl acrylate and the like; amines such as diethylenetriamine, N,N-dimethylaminopropylamine and the like; ethers such as diethyl ether, propylene oxide, tetrahydrofuran (THF) and the like; amides such as N-methylpyrrolidone (NMP), dimethylformamide, dimethylacetamide and the like; and polar aprotic solvents such as hexamethylphosphoramide, dimethyl sulfoxide and the like may be used as the absorption solution.

(25) The absorption solution and the fluid solution may be supplied in counter-flow or parallel-flow directions.

(26) The cation electrode 7c, the anion electrode 7d, the cation exchange membrane 7a and the anion exchange membrane 7b are not limited as long as they are used for a conventional fluidized-bed electrode system (battery, storage battery, etc.), and those appropriately selected by those skilled in the art based on the purpose of use and conditions can be used.

(27) Next, embodiments of the present invention using the carbon dioxide capturing apparatus capable of producing electricity will be described.

(28) In FIG. 3, reference numbers 1, 5, and 7 refer to an absorption tower 1, a heat exchanger 5, and an electricity-generating device using ion 7, respectively.

(29) The absorption tower 1 may include a flow path 2 for an exhaust gas containing carbon dioxide, a flow path 3 for an exhaust gas passing through the absorption tower, a flow path 10 for supplying a regenerated absorption solution passing through the heat exchanger 5 to the absorption tower, a flow path 4 for discharging an absorption solution that has absorbed carbon dioxide into a lower part of the absorption tower, a filler 1a that comes in contact with gas in the absorption tower, and a first liquid transfer pump 6a through which the absorption solution that has absorbed carbon dioxide is transferred to the heat exchanger.

(30) In the heat exchanger 5, heat is exchanged when the absorption solution that has absorbed carbon dioxide and the regenerated absorption solution which has passed through the electricity-generating device using ion pass through the heat exchanger.

(31) In the electricity-generating device using ion 7, a space formed between a cation electrode 7c and an anion electrode 7d is divided by a cation exchange membrane 7a and an anion exchange membrane 7b. That is, the electricity-generating device using ion 7 includes a first flow path 7f between the cation exchange membrane 7a and the cation electrode 7c, a second flow path 7g between the anion exchange membrane 7b and the anion electrode 7d, and an absorption solution flow path 7e between the cation exchange membrane 7a and the anion exchange membrane 7b.

(32) In the absorption tower 1, an absorption solution having a higher concentration than a fluid solution flowing in the first flow path 7f and the second flow path 7g is supplied to the absorption solution flow path 7e of the electricity-generating device using ion, or an absorption solution having a lower concentration than a fluid solution flowing in the first flow path 7f and the second flow path 7g is supplied to the absorption solution flow path 7e of the electricity-generating device using ion. Therefore, an ion concentration of the absorption solution passing through the absorption solution flow path 7e may increase or decrease.

(33) Then, an ammeter 8 configured to measure electric energy is connected with the electricity-generating device using ion, and thus may measure a potential difference generated by the difference in concentration in an ion generating cell.

(34) Therefore, when the absorption solution having the relatively high concentration and the fluid solution having the relatively low concentration are supplied to the electricity-generating device using ion, cations and anions move toward the absorption solution from the first flow path 7f and the second flow path 7g having a low concentration to the cation electrode 7c and the anion electrode 7d through the cation exchange membrane 7a and the anion exchange membrane 7b, so that a potential difference is generated by the moving cations and anions.

(35) On the other hand, when the absorption solution having the relatively low concentration and the fluid solution having the relatively high concentration are supplied to the electricity-generating device using ion, cations and anions move toward the absorption solution from the first flow path 7f and the second flow path 7g having a high concentration to the cation electrode 7c and the anion electrode 7d through the cation exchange membrane 7a and the anion exchange membrane 7b, so that a potential difference is generated.

(36) A conceptual diagram of the present invention is shown in FIG. 2. An absorption process of the present invention operates in a temperature range of 5 to 80 C., a pressure range of atmospheric pressure to 20 atm and a range of a molar flux ratio (liquid/gas) of 2.0 to 10. An ion exchange membrane process of an generating device using ion of the present invention also operates in a temperature range of 5 to 80 C., a pressure range of atmospheric pressure to 20 atm and a range of a volumetric flow ratio (saline water:freshwater:electrolyte) of 2:1.0 to 2.0:2. Two effects of reducing greenhouse gases by removing carbon dioxide from exhaust gases and of producing electricity by inputting an absorbent which absorbs carbon dioxide to an generating device using ion which uses a difference in concentration to generate a potential difference can be obtained based on the concept that a gas including carbon dioxide is absorbed by an absorption solution in an absorption tower, the absorption solution which has a high concentration and has absorbed carbon dioxide and freshwater which has a low concentration are supplied to an generating device using ion which utilizes the difference in concentration, and then electricity is produced by generating the potential difference in the electricity-generating device using ion in which only ions selectively permeate.

Embodiment 1

(37) In Embodiment 1 of the present invention, a carbon dioxide absorbing apparatus that is capable of producing electricity and is configured of five pairs of a cation exchange membrane (developed by Fumatech and Astom Corporation) and an anion exchange membrane (developed by Fumatech) between rectangular positive and negative electrodes (graphite electrodes) having a micro-flow path, a spacer, an absorption solution (KIERSOL: mixture of 15 wt % K.sub.2CO.sub.3, 10 wt % 2-methylpiperazine, and water), a vessel with a stirrer through which carbon dioxide is reacted (10 mL/min, 200 rpm, 40 C.), a vessel for inputting freshwater (10 mL/min) and a vessel for circulating an electrolyte (a mixed solution of ferrocyanide and NaCl:Fe(CN).sub.6.sup.3/4 50 mM, 20 mL/min), was manufactured.

(38) The total energy generated was 0.05 W, voltage was 0.5 to 0.54 V, and the maximum power density per unit area of an exchange membrane was 0.8 W/m.sup.2. FIG. 4 illustrates values of power density and closed circuit voltage based on reaction time. It can be seen that the power density values were 0.7 to 0.8 W/m.sup.2 within a measured amount of time. Generated energy per unit cell when KIERSOL was used as an absorbent was 300 kJ/(ton of KIERSOL).

(39) As shown in FIG. 5, it can be seen that a pH of freshwater passing through an ion reactor decreased to pH 7.2 from pH 8.0 before passing through the ion reactor, and a pH of the absorbent KIERSOL increased to pH 8.4 from pH 7.9 before passing through the ion reactor. HCO.sub.3.sup. and H.sup.+ ions were transferred through an ion exchange membrane, and as a result, an absorption solution was regenerated into a base solution and a fluid solution was regenerated into an acidic solution.

Embodiment 2

(40) Upon reviewing FIG. 6, experimental results of a carbon dioxide capturing apparatus capable of producing electricity can be confirmed. An experiment was performed using a selective ion exchange membrane (0.0071 m.sup.2) developed by Fumatech, a graphite electrode, five stacks of cation and anion exchange membranes, a spacer (0.2 mm), saline water (10 mL/min), freshwater (5 mL/min), and an electrolyte (10 mL/min).

(41) In the case of a KIERSOL solution, voltage was 0.3 to 0.4 V, and a power density value was 0.3 to 0.4 W/m.sup.2. In the case of a KIERSOL solution that had absorbed carbon dioxide, voltage was 0.5 V, and a power density value was 0.7 to 0.8 W/m.sup.2.

(42) While the present invention has been described with reference to the exemplary embodiments of the present invention, it may be understood by those skilled in the art that various modifications and alterations may be made without departing from the spirit and scope of the present invention described in the appended claims.