Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
  • B01D53/1456—Removing acid components
  • B01D53/1475—Removing carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D53/00—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols
  • B01D53/14—Separation of gases or vapours; Recovering vapours of volatile solvents from gases; Chemical or biological purification of waste gases, e.g. engine exhaust gases, smoke, fumes, flue gases, aerosols by absorption
• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09K—MATERIALS FOR MISCELLANEOUS APPLICATIONS, NOT PROVIDED FOR ELSEWHERE
  • C09K3/00—Materials not provided for elsewhere
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2252/00—Absorbents, i.e. solvents and liquid materials for gas absorption
  • B01D2252/20—Organic absorbents
  • B01D2252/204—Amines
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2257/00—Components to be removed
  • B01D2257/50—Carbon oxides
  • B01D2257/504—Carbon dioxide
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D2258/00—Sources of waste gases
  • B01D2258/02—Other waste gases
  • B01D2258/0283—Flue gases
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B82—NANOTECHNOLOGY
  • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
  • B82Y30/00—Nanotechnology for materials or surface science, e.g. nanocomposites
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02C—CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG]
  • Y02C20/00—Capture or disposal of greenhouse gases
  • Y02C20/40—Capture or disposal of greenhouse gases of CO2

Definitions

• the present invention rela tes to carbon capture and more particularly to polymer-encapsulated carbon capture capsules that tolerate precipitation of solids for increased capacity.
• the present invention removes the precipitation limitation of the prior art by incorporating the liquid sorbent in a thin polymer shell, forming a liquid filled bead typically 100 um to 1 mm in diameter.
• This bead is a self- contained system that can tolerate precipitation of solids during the loading phase, and that presents a uniform physical presence during the regeneration fe.g, steam stripping) phase, in this way the carrying capacity and efficiency of the incorporated liquid solvents can be increased by 25% or more.
• FIG. 1 is a pictorial illustration of a system for separating carbon dioxide from gas mixtures.
• FIG. 2 illustrates an embodiment of a system for separating carbon dioxide from gas mixtures.
• FIG. 4 illustrates yet another embodiment of a system for separating carbon dioxide from gas mixtures.
• FIG. 5 illustrates yet another embodiment of a system for separating carbon dioxide from gas mixtures.
• FIG. 6 illustrates a system for making polymer coated capsu les.
• FIG. 8 illustrates flue gas (e.g., CO?., H?C), Ni, $0>, NOd and/or other gas mixtures being processed by passing it. upwards through a absorption tower while being contacted with a suspension of polymer coated capsules.
• flue gas e.g., CO?., H?C
• the present invention uses the encapsulation methods to make liquid-filled microcapsules with very thin polymer shells.
• the present invention specifically deals with the contents of the capsules, which can be liquids or mixtures of liquids and solids.
• the fact that the polymer shell enforces very strict Limits on changes in the chemistry of the interior fluid permits that fluid to be of a composition that, during the reaction with a carbon dioxide-bearing gas, the uptake of carbon dioxide can cause solid precipitates to form in the capsule.
• a typical capture process would expose these capsules to the gas, with the uptake of carbon dioxide and eventual precipitation of solids in the capsule.
• One process t recover the carbon dioxide in pure form would be to heat the capsules to temperatures of 70 to 200 ⁇ ' C, causing the carbon dioxide to vaporize and leave the capsule.
• Other processes such as chemical changes,, or changes in the applied pressure, could be used,
• a specific example is in the use of :;CC as the capture medium.
• litis leads to a considerable increase in the carrying capacity of the system.
• the carrying capacity in this example is twice that which would be permitted it the grey box (precipitate region) were avoided, and the initial, recovery pressure is four times higher.
• An advantage is that the minimum, water can be kept in the capsule, which minimizes the vaporization of water during recovery a d concomitant energy penalty due to that vaporization.
• This invention permits the increased capacity and reduced operating concerns possible through confining the precipitates inside the capsule, and keeping the overall chemistr constrained inside the capsule.
• Water and CO are tree to exchange and move across the polymer to permit the capture reactions to occur, but no cations can move across the polymer.
• the system 100 provides a system for carbon dioxide capture from flue gas and other industrial gas sources.
• a flue gas 102 is bubbled through a slurry of water 104 and microcapsules 106. Water is optional in the process but is always present in flue gas, even it not in liquid form.
• the system 100 utilizes microcapsules .106 with very thin polymer she! is.
• the contents of the microcapsules 1.06 can be liquids or mixtures of liquids and solids.
• the microcapsules 106 are exposed to the flue gas and other mdustna! gas " 102 and take up carbon dioxide from the flue gas and other industrial gas and eventual precipitate solids in the capsules 106.
• the microcapsules 106 include a polymer coating and stripping solvents encapsulated withi the microcapsules 106,
• the polymer surface laye is permeable to carbon dioxide.
• the strippin solvents encapsulated within the microcapsules can. be any or a mixture of the following: primary, secondary , tertiary, and hindered amines, caustic solutions, ionic buffer solutions, ionic liquids, ammonia, and other solvent's having high a solubility of carbon dioxide.
• Carbon dioxide is absorbed by passing the flue gas 102 from which the carbon dioxide is to be separated through the slurry made u of water 104 and the microcapsules 106.
• the carbon dioxide migrates through the polymer coating oi the microcapsules 106 and is taken up by the stripping solvents.
• the carbon dioxide is separated by driving off the carbon dioxide from the microcapsu les.
• the carbon dioxide can be transported to an injection site for sequestration, and long-term storage in any of a variety of suitable geologic formations.
• 200 can be an or a mixture of the following: primary, secondary, tertiary, and hindered amines, caustic solutions, ionic buffer solutions, ammonia, ionic liquids, and other solvents having high a solubility of carbon dioxide.
• the microcapsule 200 is used to capture carbon dioxide from gas mi tures.
• the ccmtacting device can be one of several configurations including a fSuidized bed, a countercurrent flow, suspended in an aqueous liquid, etc.
• the capsules are typically regenerated thermall in a controlled environment where the carbon dioxide is released in pur form suitable for compression and injection into the subsurface.
• the environment could be that of steam at a partial pressure such that is it in equilibrium with water inside the capsules to prevent water transport into or out of the capsule. Dry heat from a heat exchanger or oil bam amid optionally be used at this stage.
• the encapsulation of amines within a spherical polymer shell in accordance with the present inven tion has advantages over conventional amine capture systems.
• isolating the amines within the polymer shell can limi degradation of the solvent and prevent migration of any degradation products formed, thereby reducing corrosion of the capture system. This allows for higher concentrations of solvent and thus higher loadings of CCte, reducing the energy needed for regeneration.
• Equipment may be smaller an eonstracted out of less expensive materials, for instance carton steel in place of stainless steel,, when the corrosion products are contained withi the capsules and unable to react with the capture device.
• Second, encapsulation allows novel process designs.
• a capture system based on encapsulated amines may look Like a flukiized bed as opposed to a con entional packed tower.
• the beads can be agitated ei ther by the Sue gas (or stripping gas) or run as a hatch process.
• This new process concept can take advantage of the encapsulation during regeneration by using a stripping that has a lower boiling point and heat of vaporization than water (e.g.
• the present invention provides benefits in fabrication and
• the beads can be fabricated at a size small enough for efficient mass transfer and large enough tor ease of handling.
• the presen inven ion provides methods to fabricate liquid filled shells in the size range of 100 microns to .1 mm. with wall thickness fr m 5-10 microns.
• the present invention provides benefits in rvivability and robustness.
• the presen inven ion identifies several polymers that can withstand typical regeneration temperatures of 100-120" C
• the selected polymers will be capable of withstanding small volumetric changes due to absorption desorption of CO?, and water.
• Applicants have determined from data on the densities of common CO:; solvents that loading and unloading cycles will not cause a volume increase such that the microcapsule is likely to burst.
• the microcapsule 200 shown in TIG. 2 can be used to illustrate other embodiments of the present invention.
• the microcapsule 200 is illustrative of a system utilizing microcapsules having a coating 202 and stripping material
• the coating 202 is permeable to the target substance and the target substance migrates through said coating 202 and is taken up by the strippin material 204.
• the target substance is capture by driving off the target substance from the microcapsule 200 thereby separating the target substance from the fluid or mixture.
• the coating 202 is made of a porous solid.
• the coating 202 includes carbon fibers, in yet another embodiment the coating 202 includes carbon nanotubes.
• the carbon be can be used to provide strength and resilience to the microcapsule 200.
• the carbon nonotubes can aligned to improve and control permeability of the coating 202.
• the coating 202 is made of any of several families o -polymers, including polystyrene, polyethylene, polypropylene, and nylon.
• the surface layer 202 is optimally less than 10 microns thick and is very permeable to the target substance.
• the stripping solvents 204 encapsulated within the microcapsule 200 can be primary, secondary, tertiary, and hindered amines, caustic. solutions, ionic buffer solutions, ammonia, or other solvents having solubility of carbon dioxide encapsulated in the microcapsules
• the stripping solvents 204 encapsulated within the microcapsule 200 can be nitrous oxide wherein the nitrous oxide migrates through the coatin 202 and is taken up by the stripping material 204.
• the stripping solvents 204 encapsulated within the microcapsule 200 can be sulphates wherein the sulphates migrate through the coating 202 and are taken up by the stripping material 204.
• the stripping solvents 204 encapsulated within the microcapsule 200 can be hydrogen sulfide wherein the hydrogen sulfide migrates through the coating 202 and is taken up by the stripping material 204.
• the present invention is further explained by a number of examples.
• the examples further illustrate Applicants ' ' system for separating carbon dioxide from a gas mixture
• the gas mixture and the carbon dioxide are dissolved in water providing water with, the dissolved gas and carbon dioxide.
• the microcapsules have a polymer coating and stripping solvents encapsulated withi the microcapsules.
• the microcapsules containin the stripping solvents are exposed to the water with the dissolved gas and carbon dioxide.
• the carbon dioxide migrates through the polymer coating and is taken up by the stripping solvents.
• the carbon dioxide is separated by driving off the carbon dioxide from the microcapsules.
• Step 1 (Reference Numeral 302) ⁇ Flue gas (e.g., CO3 ⁇ 4 HJO, NbSC , NCX) and/or other gas mixtures 301 is processed in a water wash 303.
• Flue gas e.g., CO3 ⁇ 4 HJO, NbSC , NCX
• other gas mixtures 301 is processed in a water wash 303.
• system/process 300 is thus designed to dissolve flue gas and/or other gas mixtures first in slightly alkaline water as introduced by the wafer wash 303 prior to producing a concentrate from which a harvested CO; can be produced.
• the water wash 303 system itself can be incorporated from known systems utilized by those of ordinary skill in the art.
• the common system can include a plurality of spray levels to inject the liquid so as to contact the fine gas, which is designed to flow through such a water wash 303 at a predetermined constant velocity.
• the number of spray levels can be varied depending on the effective liquid to gas (L/G) ratios.
• spray nozzles of different sizes producing different flow rates, spray patterns, and droplet sizes ca also be utilized.
• Step 2 (Reference Numeral 30 )--The water containing the flue gas passes from water wash 303 to an area wherein microcapsules 305 are added forming a slurry 307 of water, microcapsules 305, CO2, and the impurities.
• Carbon dioxide is absorbed by passing the gas from vvhich the carbon dioxide is to be separated through the slurry 307 either b bubbling, use of an absorber tower, or any other means suitable for absorbing a gas into a liquid.
• the process for absorbing carbon dioxide or other acid gases is similar to the process used in amine stripping.
• the water can also be a process fluid that is " 1.00% recycled (not purified) during the desorptlon stage., but this is less than optimal.
• the C ? or other acid gases dissolve in the water and are then absorbed by the microcapsules 305, permitting more to dissolve into the water until saturation Is reached,
• Step 3 (Reference Numerals 308, 309, 310, & 311)--The mixture of microcapsules containing the CO: is then heated 309 to the boiling point of water (typically lOO.degree, C.) to release the CO2 from the microcapsules 305, During the heating 309 step steam 311 is produced.
• the heating 309 step steam 311 is produced.
• carbon dioxide is freely evolved at slightl below 100 degree C in pure water. This is because there is relatively little carbon dioxide gas in the water (it's partial pressure (fugacity) is lower).
• Step 4 (Reference Numerals 312 & 313)--The steam 311 is condensed by cooling 313,
• example 2 a system for simultaneous water purification and carbon dioxide removal from gas mixtures is described and illustrated.
• Example 2 is illustrated by the method i llustrated in FIG. 4.
• the method is designated generall by the reference numeral 400.
• the steps of the method 400 are described below.
• Step 1 (Reference Numeral 402 ⁇ ⁇ Flue gas (e.g., CO3 ⁇ 4 HA NbSC NO * ) and/or other gas mixtures 401 is processed in a water wash 403.
• the system/process 400 is thus designed to dissolve flue gas and/or other gas mixtures first in slightly alkaline water as introduced b the water wash 403 prior to producing a concentrate from which a harvested CC can be produced.
• the water wash 403 system itself can be incorporated from known systems utilized by those of ordinary skill in the art.
• the common system can include a plurality of spray levels to inject the liquid so as to contact the flue gas, which, is designed to flow through such a water wash 403 at a predetermined constant velocity.
• the number of spray levels can be varied depending on the effective liquid to gas (L/G) ratios.
• spray nozzles of different sizes producing different flow rates, spra patterns, and droplet sizes can also be utilized.
• Carbon dioxide is absorbed by passing the gas from which the carbon dioxide is to be separated through the slurry 407 either by bubbling, use of an absorber tower, or any other means suitable for absorbing a gas into a liquid.
• the process for absorbing carbon dioxide or other acid gases is similar to the process used in amine stripping.
• the mixed gas is passed through or over a solution of the water containing the microcapsules 405.
• the water is any water which is desired to be purified during the desorption step. This can be sea water, brine, water compromised by any low-volatility salt or other dissolved component.
• the water can also be a process fluid th t is 100% recycled (not purified) during the desorption stage, but this is less than optimal.
• the CO? r other acid gases dissolve in the water and are then absorbed by the microcapsules 405, permitting more to dissolve into the water until saturation is reached,
• Step 4 (Reference Numerals 41.2 & 413)----The steam 41 1 is condensed by cooling 41.3,
• Step 5 (Reference Numerals 414 & 15) ⁇ -Condensing of the steam 411 produces fresh water 415, With a buffer media that i easi ly separable (by filtration) from the working liquid medium, it is now possible to use a brin or other compromised water as the feedstock. During the regeneration step the steam witich must necessarily be produced can be condensed as fresh water obtaining dual benefit for the energy required to regenerate the CO::. None of the buffer material carries over into the distillate unlike the fairly volatile amines currently used.
• Step 6 (Reference Numerals 416 &. 417)--Condensing of the steam 41 1 purifies the gas stream coming out of the process to nearly pure CO? 417.
• the CO;: 417 can be used or sequestered.
• the COs 417 can he transported to an injection site for sequestration and long-term storage in any of a variety of suitable geologic formations.
• Step 7 (Reference Numerals 416 & 417 ⁇ - Condensing of the steam
• example 3 a system for simultaneous water purification and carbon dioxide removal from gas mixtures is described and illustrated.
• Example 3 is illustrated by the method illustrated in FIG. 5.
• the method is designated generally by the reference numeral 500.
• the steps of the method 500 are described below.
• Step 1 (Reference Numeral 502) ⁇ ⁇ Flue gas (e.g., Ch, HO, ;£0,, NOx) and/or other gas mixtures 501 is processed in a water wash 503,
• the system/process 500 is thus designed to dissolve flue gas and/or other gas mixtures first in slightly alkaline water as introduced by the water wash 503 prior to producing a concentrate from which a harvested COsca.n be produced.
• the water wash 503 system itself can he incorporated from known systems utilized by those of ordinary skill in the art.
• the common system can include a pluralit of spra levels to inject the liquid so as to contact the flue gas, which is designed to flow through such a water wash 503 at a predetermined constant velocity.
• the number of spray levels can be varied depending on the effective liquid to gas (L/G) ratios, in addition, spray nozzles of different sizes producing different flow rates, spray patterns, and droplet sizes can also be utilized.
• Step 2 (Reference Numeral 504)— The w er containing the flue gas passes from water wash 503 to an area wherein microcapsules 505 are added forming a slurry 507 of water., microcapsules 505, CO:;, and the impurities.
• Carbon dioxide is absorbed by passing the gas from which the carbon dioxide is to be separated through the slurry 507 either by bubbling, use of an absorber tower, or any other means suitable tor absorbing a gas into a liquid.
• the process for absorbing carbon dioxide or other acid gases is similar to the process used in amine stripping.
• Step 3 (Reference Numerals 508, 509, 510, & 51 l) ⁇ The mixture of • microcapsules containing the CCfe is then heated 509 to the boiling point of water (typically lOO.degree. C.) to release the CO ⁇ from the microcapsules 505. During the heating 509 step steam 511 is produced. in.
• Step 4 (Reference Numerals 512 & 513)TMThe steam 511 is condensed by cooling 513.
• Step 5 (Reference Numerals 5 4 & 515)--Condensing of the steam 511 produces fresh water 515.
• a butter media that is easily separable (by filtration) from the working liquid medium, it is now possible to use a brine or other compromised water as the feedstock.
• the steam which must necessarily be produced can be condensed as fresh water obtaining dual benefit for the energy required to regenerate the CO2, None of the buffer material carries over into the distillate unlike the fairly volatile amines currently used.
• One advantage is longer buffer life by reduced temperatures and isolation of the buffer material from oxygen.
• Step 7 (Reference Numerals 516 & 517) - Condensing of the steam
• FIG, 6 illustrates a system for ma king polymer coated
• FIG. 6 illustrates a system and method of fabricating double- emulsion mi crocapsul.es.
• the schematically illustrated method 600 will be composed of the following items.
• the injection tube 602 with a ID (um) and OF) 1000 (um) .
• a collection ttibe 604 with an ID of 500 (um) and QD 1000 (um) and an outer rube 606 of square cross section with ID of 1000 (urn) and ID of 1200 (um).
• U.S. Patent No. 7,776,927 to Liang-Yin Chu et at assigned to the President and Fellows of Harvard College discloses emulsions and the production of emulsions, including multiple emulsions and mfcrofi idic systems for producing mul iple emulsions.
• a multiple emulsion generall describes larger droplets that contain one or more smaller droplets therein which, in some cases., can contain even smaller droplets therein, etc.
• Emulsions including mul iple emulsions, can be formed in certain embodiments with generally precise repeatability, and can be tailored to include any number of inner droplets, in any desired nesting arrangement, within a single outer droplet.
• one or more droplets may be controllable released from, a surrounding droplet, U.S. Published Patent
• a multiple emulsion describes larger droplets that contain one or more smaller droplets therein.
• the larger droplet or droplets may be suspended in a third fluid in.
• emulsion degrees of nesting within the multiple emulsion are possible.
• an emulsion may contain droplets containing smaller droplets therein, where at least some of the smaller droplets contain even smaller droplets therein, etc.
• Multiple emu lsions can be useful, .for encapsulating species such as
• one or more of the droplets can change form, tor instance, to become solidified to form a microcapsule, a lipo some, a polyme.ro some, or a colloidosome.
• multiple emulsions can be formed in one step i certain embodiments, with generally precise repeatability, and can be tailored to include one, two, three, or more inner droplets within a single outer droplet (which droplets may all be nested in some cases).
• the term "fluid” generally means a material in a liquid or gaseous state. Fluids, however, may also contain solids, such as suspended or colloidal particles.
• Encapsulated solvents can be used to capture carbon dioxide from power plant flue gas.
• the limiting step in mass transfer is probably diffusion across the polymer membrane.
• the mass transfer rate is then, proportional to the permeability of the membrane.
• Permeabilit has a wide range of values for different polymers. A permeability for CCbof 100 barrer is chose as a
• encapsulated solvents At 100 barrer permeability, 200 .una diameter, and 5 fan wall thickness, encapsulated solvents have about 2 orders of magnitude slower absorption per unit surface area than conventional liquid solvents.
• a bed of spherical beads is explored as a system design. With 200 fa diameter beads and close spherical packing, such a bed has 2 orders of magnitude higher surface area per unit absorber volume than a conventional packed tower using a liquid solvent. High pressure drop appears to be the primary drawback of this configuration, which is estimated to be orders of magnitude larger than for a conventional packed tower. The high pressure drop is largely due to the low proportio of void space in tight-packed spheres (36%- 40%, compared with 90-97% in commercial tower packings).
• a system based on a packed bed of beads will he viable if a higher permeability can be achieved ⁇ on the order of .1000 barrer), or if more void space can be introduced to the system (e.g. a doubling), in. principle, resistance to mass transfer of CO?, into (or out of) the bead can occur In three zones: (1) from the bulkgas to the surface of the polymer shell (gas-phase resistance), (2) through, the polymer shell (membrane resistance)., and (3) from the inner surface of the shell to the bulk of the inner fluid (liquid -phase resistance). For this calculation.
• Equation 1 where ⁇ is the pressure drop across the membrane, L is the thickness of the membrane, and P Is the permeability coefficient of the polymer.
• the CCte pressure on the outside of the shell is the gas-phase partial pressure in the tine gas. Since Applicants assume the inner fluid is a fast solvent, the effective CO- pressure on the inner wall of the shell is the equilibrium partial, pressure of CCb above the solvent at the appropriate tem erature and carbon loading. This Is generally small compared to the partial pressure in the flue gas. For example, flue gas typical ly starts at 15% CO - 0.15 aim - 15200Pa.
• the equilibrium partial pressure of CC for 5M Monoethanolaniine (ME A.) at 40°C and 0,3 rnoi CC /moi amine is 22 Pa, So tor our purposes, Ap is equal to the partial pressure of COs in the flue gas.
• the synthetic polymer with the largest measured permeabi lities is poly(l-trimethylsiiyipropyne). This polymer possesses a carbon dioxide permeability of 28 000 barrer and a nitrogen permeability of 4970 barrer. These very large permeabilities are associated with a very large fractional free volume. These permeabilities tend to decrease with time due t slow crystallization of the polymer. This effect can be counteracted by the addition of certain additives.
• Equation 1 is analogous t the classic mass transfer equation, across an interfaciai boundary: where K is the overall mass transfer coefficient and AC is the concentration difference between, in our case., the bulk flue gas and the equilibrium partial pressure of CQz above the solvent.
• volume of gas per unit volume absorber is:
• the pressure drop across a perforated plate ⁇ 3 ⁇ 4. «> consists of losses from com ression of the gas i to the holes, friction through the holes, and then expansion on the other side.
• the following expression can be used for calculating the pressure drop across a dry., perforated plate.
• the terms within the brackets address those three kinds of losses, respectively:
• Is ik ve riv of gas inside Ik o jiit/sj, v id3 ⁇ 4 is refoi ⁇ 3 ⁇ 4i to i c siiixdnai velocity by: 14 ⁇ T ⁇ . ⁇ e / is ife i' r:;iiii ⁇ ' ⁇ iklor, ife ⁇ 'ii3 ⁇ 43 ⁇ 4i j
• the Fanning friction factor (equal to one fourth of the Darc friction factor) is a function of the Reynolds number of the system, Re, which for flow through smooth . , circular pipes, and correcting the superficial velocity to the velocity inside the holes, is defined by:
• Re ranges from 0,32 to 32, which is solidly in the laminar flow regime (for flow in a pipe, Re ⁇ 2300 is generally laminar). In the laminar regime; Applicants can. calculate the Fanning friction factor by:
• the last parameter to consider is the fraction of open area, Ah/Ac.
• Perforated metals are commonly available with open area up 60% (1 PA, 1993), however, that come at the price of reduced strength. At 20% open area, strength is reduced by about 50%; at 60% open area, strength is reduced to " 15-20% of solid-plate strength. Applicants have assumed 20% open area.
• a plicants have 200 um beads with 400 barrer permeability.
• the superficial velocity required to achieve 90% capture is 0.18 m/s. At this rate.
• Applicants need 49 commercial grain dryer-sized units to handle a 430 MWe coal plant. Each operates with a pressure drop of 34.7 kPa across the bed and 0.25 kPa across the inner and ou er walls (assuming 1.2 mm wall thickness). In energ terms..
• Mass transfer through a series of media can be described by the electrical resistance model, where the resistance, R, is the inverse of the mass transfer coefficient, K. If Applicants neglect gas-side resistance ⁇ which is probablv a good assumption), then Applicants have: _J 1 ⁇ I
• the equivalent shell permeability is 10,000 barrer. if Applicants had. a shell with 1,000 barrer permeability, then the solvent would be
• a catalyst could speed the rate of mass transfer by, at most, 9%. If Applicants had a shell with permeability of 10,000, then a. catalyst could speed the rate of mass transfer by, at most, 50%.
• K depends on. a number of factors, such as turbulence in the measurement system., temperature, and precise composition of the solution, so these values should he taken, as order-of-magnttude guides only.
• d e highest measured permeability for a polymer membrane is 28,000 barrer, it seems apparent tha a catalyst would not be very helpful in beads filled with, a fast-reacting solvent like MEA.
• the catalyst should be helpful for a slower solvent like sodium bicarbonate, paired with a membrane with permeability of a few hundred barrer or higher.
• FIG. 7 shows a cross section of a microcapsule 702.
• 704 is a layer of catalyst or enzyme added to enhance th reaction, rate of carbon dioxide to dissolved carbonate. This may be either dissolved in the polymer, the solvent, or as a separate layer (a triple emulsion) during bead creation
• FIG. 7 shows the addition of fibers, nanotubes, or other permeability -enhancing compone s 7-6 that improve the permeability of the capsule, or its strength or abrasion resistance.
• These could include carbon nanotubes, silicon carbide, n lon, or a variety of other materials that enhance the basic function of th polymer shell, in. the case of 706 the fibers are oriented along the shell radius for purposes of strength improvement or abrasion resistance.
• Example 5 a system for carbon dioxide removal from gas mixtures is described and illustrated.
• Example 5 is illustrated by FIG, 8 showing a method of separating CO ⁇ .
• the method is designated generally by the reference numeral 800.
• the steps of the method S00 are described below.
• the solvent may be an amine, an inorganic base, or any other solvent which has a. high capacity for take-up of CDs. Preferential partitioning of CO? into the capsule is due t the relatively higher solubility of CO? in the
• the capsules remain in the gas stream, unti l they contain sufficient CO2 such that they are ready for removal, from the gas contactor for transport to the regenerator where the contained CO2 will be removed.
• the capsules remain in the system for some period of time before they are entirely removed from the system,. As such the system is operated, in a batch mode,
• the capsules are fed and removed
• the capsule solvent is chosen and designed such that as the capsules load with CC3 ⁇ 4 they become progressively more dense than unloaded capsules and as a consequence the loaded capsules self-separate and drop to the bottom of the tower where they are removed for transport to the regenerator described in Step 2. As such the system operates in a continuous mode.
• the capsules contact the mixed gas stream in a rotating tipped cylinder such that the capsules form a bed residing on the lower surface of the rotating cylinder and cascade down the length of the cylinder, while the gas stream passes upwards through the c linder contacting the cascadin capsules.
• the capsules are removed and cycled back to the top for additional loading.
• the system may be operated either in batch or continuous mode. The advantage for this contact method is that the capsules no longer must be sufficiently buoyant such that they form, a i!ukiixed bed in the gas tower,, as is the case for the other contact scenarios.
• the solvent contained within the capsule is chosen such that is has a preferentially high solubilit of CO; and low solubility of other gas stream components such as nitrogen and oxygen. Solvents that are alkaline have this property because the CO? will ionise in. them to form bicarbonate (HCC -) and carbonate (CO.?-) species which are highly soluble in aqueous solutions and in aqueous solutions of amines.
• the solvent of choice may be an amine such as methylethanolamine (MEA) or other amine- based solvents that have high solubilities for CO?
• the solvent may be an inorganic solution of a base, such as sodium hydroxide, potassium carbonate, sodium, borate, or sodium, phosphate or any of many Cither inorganic solvents that are bases in the sense of acid-base reactions, and have high solubilities of carbon dioxide.
• I is the solvent th provides selectivity for COx.
• the capsule wall will be permeable to ail of the gas components including water, and does not provide selectivity for C02.
• Step 2 (Reference Numeral 800) --The loaded "fat" capsules from Step 1 are now ready for CCh extraction ''regeneration" in order to produce a concentrated COz stream.
• the goal is to produce a relatively pure stream, of CCfe such that it can be compressed to a liquid form for transport or storage.
• the derived CO2 stream must not contain appreciable amounts of non- condensable gases such as nitrogen, oxygen or argon.
• Regenera ion to remove the contained CCh is carried out by heating the capsules to an elevated temperature where the equilibrium content of CO2 is much lower than the equilibrium conten t of CO2 during collection from the mixed gas stream.
• the temperature may be around 100 C or may be a much higher temperature.
• the optimal temperature of regeneration depends on. the type of solvent contained within the capsule and the CCh loading.
• the capsules may he regenerated by contacting them with hot steam, which will produce a gas containing mainly CCh and H?.0, and which upon cooling will self-separate into a dommant!y CO? gas phases and liquid water (Step 3).
• the capsules may be regenerated b heating in pressurized liquid water which will upon lowering of the containing pressure vvill produce a stream of relat ely pure CO?.
• Step 3 (Reference Numeral 800) ⁇ -
• the regenerated capsules that have been thermally treated are now have low CO; contents ("lean”) arid are suitable for another cycle of CO2 capture.
• the capsules may he removed from the gas or liquid water using a mechanical filter of any of a variety of type and designs. The separated capsules are then returned to Step 1 to begin another cycle.

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• 2012
  • 2012-10-26 EP EP12843330.7A patent/EP2771096A4/de not_active Withdrawn

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