JP2011504806A - Carbon dioxide capture and long-term sequestration methods and means - Google Patents

Abstract

It is a practical method for recovering CO ₂ from a gas mixture and sequestering the captured CO ₂ from the atmosphere as calcium carbonate for the geological age, and provides a CO ₂ scrubber for carbon capture and sequestration. CO ₂ scrubber, liquid - incorporating aqueous froth to maximize the contact time between the gas area and gaseous CO ₂ and calcium hydroxide solution. The CO ₂ scrubber reduces the temperature of the liquid and gas mixture, increases the ambient pressure on the bubbles and the vapor pressure within the bubbles, and through the inter-bubble walls from small bubbles with high vapor pressure to large bubbles with low vapor pressure. Te diffuses the gas and to reduce the mean free path of the CO ₂ molecules in the bubbles, increasing the dissolution rate of the gaseous CO ₂ from the solubility and the gas mixture CO ₂ into calcium hydroxide solution.

Description

This application is a continuation-in-part of US patent application Ser. No. 11 / 729,253, filed Mar. 28, 2007. This application claims the benefit and priority of the following US provisional application:
1) US 61 / 004,446 filed on November 27, 2007 2) US 61 / 007,213 filed on December 11, 2007

The Intergovernmental Panel on Climate Change (IPCC) has linked the increase in average global temperature to increasing carbon dioxide (CO ₂ ) concentrations in the Earth's atmosphere. Anthropogenic fossil fuel combustion, and the resulting CO ₂ emissions, have been correlated as a factor in the current average global temperature increase rate.
Practical solutions to carbon capture and sequestration (CCS) use abundant natural resources, mix these natural resources with CO ₂ and recycle them back into the product, or sell to offset CCS costs It creates the necessities that can be done and provides long-term sequestration of CO ₂ from the atmosphere.

Calcium, the fifth most common element in the Earth's crust, is also one of the most widely distributed inorganic substances on the Earth's surface. In fact, calcium reacts with oxygen (O ₂ ) to form unstable calcium oxide. Calcium oxide reacts rapidly upon contact with carbon dioxide (CO ₂ ) to produce extremely stable calcium carbonate (CaCO ₃ ).
Since it is unstable, calcium oxide does not exist in nature and must be produced synthetically. Calcium oxide is produced by heating limestone to sublime CO ₂ from calcium carbonate to produce calcium oxide and gaseous CO ₂ . With respect to the CCS process described herein, gaseous CO ₂ released during the production of calcium oxide is geologically sequestered. From the viewpoint of environmental problems, calcium oxide produced responsibly is transported from the production site to the CCS point.

Calcium oxide yields calcium hydroxide (Ca (OH) ₂ ) when it is quenched with water. When calcium hydroxide is dissolved in water, it is dissociated into calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ ). When CO ₂ comes into contact with calcium ions and hydroxide ions in solution, insoluble and extremely stable calcium carbonate (CaCO ₃ ) precipitates from the solution.

Calcium carbonate precipitates are used as paint extenders, plastic fillers, acid soil and water neutralizers, slope stabilizers, fluidizers, inorganic fillers, and admixtures for Portland cement . Calcium carbonate (limestone) mineral filler increases the bond strength between aggregate and cement in concrete mixes, thereby building roads, runways, taxiways, bridges, dams and reservoirs Increases load bearing capacity and wear resistance in concrete and reduces water permeability. Limestone mineral fillers are widely used in applications such as readymix, precast and self-solidifying concrete. Limestone mineral fillers always produce white products due to their pure calcium carbonate composition, making limestone fillers optimal for precast or construction site cast concrete products. Limestone is processed into two different grades (3 and 10) with particle sizes generally ranging from 1.4 to 3.2 μm and 3.2 to 10 μm. The limestone mineral filler particles from the CO ₂ scrubber are smaller in diameter than the typical Type 1 Portland cement aggregate diameter and can require less cement material, resulting in savings.

  The global production of hydraulic cement in 2005 was 2.3 billion metric tons. After water, cement is the second most used essential item by humans.

In general, the present invention relates to CO ₂ capture and sequestration. In particular, the present invention describes a unique bubble column reactor / scrubber and teaches a novel process for efficient separation of CO ₂ from gas mixtures and mineral sequestration of captured CO _2. To do.

  In US Pat. No. 6,872,240, patented 29 March 2005, entitled “Method and Apparatus for Filtration of Air Flow Using Aqueous Floss with Nucleation”, Pellegrin Disclosed is an aqueous-floss air (AFA) filter, and further states that “the incoming air stream is saturated with fine mist generated using a specially designed spray nozzle that quickly supersaturates the incoming air stream. And “but not limited to, the controlled conditions inside the filter allow smaller microdroplets and vapor formation, counteracting the evaporation seen in nature”. The bubbles are cooled on a “cold, preferably metal surface”, and an important operational point is that “submicron-sized contaminants in the air act as agglomerated nuclei causing heterogeneous nucleation and contamination. It was emphasized that “the substance is effectively trapped in the airborne fluid aerosol”.

  In an alternative scaled-up embodiment of an AFA filter using prior art nucleation (see FIG. 10 of US Pat. No. 6,872,240), at the bottom of the bubble column, the surface of the liquid reservoir Bubbles are generated on the lower side and move upward through the bubble column. The ambient pressure in the bubble and the vapor pressure in the bubble decrease continuously as the bubble moves up through or with the bubble column. Thus, increased pressure on or in the bubble is not incorporated to maximize gas absorption into the solution.

In the CO ₂ scrubber of the present invention, the bubbles are produced by a floss generator located at the top of the bubble column and flow downward. The ambient pressure for the bubbles increases continuously as each bubble flows with the bubble column in the reaction chamber. As explained by Laplace's law, as the ambient pressure increases, the bubble diameter decreases, the bubble wall tension increases, and the vapor pressure within the bubble increases. In the CO ₂ scrubber of the present invention, gas enclosed in bubbles including gaseous CO ₂ diffuses using a volume difference and a vapor pressure difference through a common bubble wall between adjacent bubbles. A gas in a relatively small bubble having a relatively high vapor pressure diffuses through the common bubble wall into a bubble having a relatively large volume and a relatively low vapor pressure. As a result, the CO ₂ scrubber of the present invention incorporates increased pressure on and in the bubbles to maximize the absorption of gaseous CO ₂ into the calcium hydroxide solution.

  A prior art AFA filter using nucleation is described, for example, in US Pat. No. 6,872,240, where the incoming air flow is “a specially designed spray nozzle. Saturated with fine mist generated using '', and micro droplets inside the bubble are generated by heterogeneous nucleation, and the phase change from vapor to liquid inside the bubble floats in the air inside the bubble Deposit on the aggregated nuclei. In an AFA filter with nucleation, the liquid and vapor are cooled “cold, preferably on a metal surface”, and by a phase change from supersaturated vapor to liquid in the bubbles in the reaction chamber of the filter. Microdroplets are formed.

In the CO ₂ scrubber of the present invention, the filtered solution is preferably cooled before the solution is pumped into a froth generator (foam). As the gas mixture, solution droplets and bubbles travel through a series of saturated mesh panels in the floss generator, the microdroplets formed by rupturing the bubbles and the crushed liquid on the preceding mesh panel The drop is contained within a bubble that is then reformed on a continuous mesh panel. At the time of creation of the present invention, the microdroplets contained within the bubbles are part of a larger liquid structure and are not the result of a physical state change from vapor to liquid. In the present invention, the microdroplet is contained in the bubble before it leaves the floss generator and while the bubble is formed.

  In the AFA filter described in Patent Document 1 using nucleation, bubbles are formed when gas is introduced below the surface of the filtration solution, and then on the aggregated nuclei floating in the air in the bubbles. In order to cause heterogeneous nucleation of steam, it is cooled by mechanical means. Microdroplets are formed within the bubbles after the bubbles enter the nucleation chamber.

In the CO ₂ scrubber of the present invention, the solution is cooled before entering the floss generator. A wide range of microdroplet radii, including Kelvin-limited microdroplets, are contained and formed within the bubble as part of the bubble burst. A relatively hot and dry mixed gas stream, as well as individual volumes of relatively cool microdroplets and vapors are enclosed within the relatively cool bubbles. The relatively hot gas evaporates the Kelvin critical microdroplets in the bubbles. Although microdroplets with minimal weight evaporate, the water in the calcium hydroxide solution increases its volume by 1600 times as it expands as a vapor, resulting in an increase in vapor pressure within the bubbles. The sensible heat of the gas is converted to latent heat to expand the water molecules from liquid to gas, rationally cooling the gas in the bubbles. As the relatively cool mass of liquid in the bubble wall enclosing the relatively hot gas cools the gas, the dew point in the bubble is reached. Condensed vapor has an affinity for the same liquid surface, and the liquid that has initially evaporated in the vapor is a micro-particle that was originally enclosed in the bubble during bubble formation immediately after the bubble formation. It condenses on the droplets, thereby increasing the mass and diameter of the microdroplets in the bubbles over time.

  In the AFA filter described in Patent Document 1 using nucleation, a mixed gas stream is introduced below the surface of the filtrate solution reservoir through a diffusion mechanism. The weight of the solution above the gas outlet should be moved by the gas pressure, resulting in a relatively high pressure drop across the diffusion mechanism. Large bubbles are created in the solution reservoir, rising rapidly through the floss column, and forming a stable channel that penetrates the floss column, which allows a portion of the gas flow to make liquid-gas contact with the solution. Can be bypassed. As the height of the floss column increases, the pressure drop across the diffusion mechanism increases. Thus, in an AFA filter with nucleation, gravitational acceleration is not used to reduce the energy required to form the bubble column.

In the CO ₂ scrubber of the present invention, bubbles are generated above the bubble column by a froth generator at the top of the reaction chamber. The solution is pumped to a floss generator to saturate the mesh panel assembly. A flow of mixed gas containing gaseous CO ₂ is forced into a saturated mesh panel to form a bubble column. Bubbles discharge downward into the reaction chamber. In the CO ₂ scrubber of the present invention, the mesh panel is positioned to be orthogonal to the mixed gas flow and gravitational acceleration, reducing the energy required to pass the solution and gas flow through the mesh panel. In addition, the liquid froth matrix of the bubble column forms a fluid plug in the reaction chamber, preventing gas from bypassing the bubble column, i.e. passing through the bubble column. As the bubble column exits the reaction chamber, a relatively low air pressure is formed at the top of the reaction chamber. The potential energy accumulated in the bubble column is partially converted into the kinetic energy of the bubble column flowing out of the reaction chamber, and also part of the kinetic energy of the mixed gas flow and solution drawn through the mesh panel as the bubble column. Converted. Thus, in the CO ₂ scrubber of the present invention, gravitational acceleration is incorporated to reduce the energy required to create the bubble column.

Conventional technology
Econamine FG + amine-type CO ₂ capture system with CO ₂ compression In a monoethanolamine (EMA) scrubber according to the prior art, flue gas flows into the contact tower and passes through the descending amine solution To rise. CO ₂ and H ₂ S are removed by chemical reaction with dilute amine solution. The purified combustion exhaust gas flows out from the top of the tower. The concentrated amine solution then carries CO ₂ and H ₂ S which are the absorbed acid gases. The diluted amine solution returning from the heating stage for releasing the acid gas and the concentrated amine solution carrying CO ₂ and H ₂ S pass through the heat exchanger and heat the concentrated amine. Thereafter, the concentrated amine of the acid gas is further heated in the regenerative distillation column by the heat supplied from the reboiler. The vapor passing up the distillation column liberates CO ₂ and H ₂ S and regenerates the amine. Vapor and acid gas separated from the concentrated amine are condensed and cooled. The condensed water is separated in a reflux accumulator and returned to the distillation column. The hot, regenerated dilute amine is cooled in a solvent air cooler and refluxed to the contact tower to complete the circulation cycle.

US Pat. No. 6,872,240

Disadvantages:
Low capital steam that requires high reaction heat and a large amount of regenerative energy (1500-3500 Btu / lbCO ₂ removal) requires 10 ppm of sulfur that reduces power generation efficiency by 20-40%, resulting in high capital that causes equipment deterioration and corrosion And operating costs

The present invention includes a method for separating gaseous CO ₂ from a gas mixture with high selectivity and sequestering CO ₂ from the atmosphere for the geological age, and also comprising a bubble column reactor / scrubber for carbon capture and sequestration. explain. Gaseous CO ₂ is captured and sequestered directly from the atmosphere, post-combustion exhaust gas, and mixed gas streams from processes that release gaseous CO ₂ as a result of processing. The mesh panel assembly is saturated with a solution containing calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ ). A mixed gas stream comprising gaseous CO ₂ is passed through a saturated mesh assembly to form an aqueous floss, with the froth bubbles having an internal volume filled with a discrete volume of mixed gas. At least some of the bubbles are ruptured and reformed, and the ruptured bubbles form a large number of microdroplets with various radii including the Kelvin critical radius, each reshaped bubble being a separate volume of gas flow, Enclose individual numbers of microdroplets and individual volumes of solution vapor. The size of the bubbles formed in the calcium hydroxide solution is limited by limiting the size of the mesh panel opening, thereby forming innumerable uniform small bubbles, CO ₂ molecules, microdroplets, Maximize contact between the inner and outer surfaces of countless small bubbles.

The solution is preferably cooled before passing through a saturated mesh panel. The cooled solution cools the gas enclosed within the bubbles as they move downward through the reaction chamber. When the relatively hot gas evaporates the microdroplets, the sensible heat is converted to latent heat to separate the calcium hydroxide solution molecules into the gas, thereby significantly cooling the gas in the bubbles. Even if the microdroplets that evaporate are small, the water of the calcium hydroxide solution increases its volume by 1600 times as it evaporates, thereby increasing the vapor pressure in the bubbles. The gas stream is conveyed downward in the reaction chamber by bubble columns, each increasing the reaction time between the gas stream and a myriad of small bubbles and increasing the ambient pressure of the aqueous floss, thereby increasing the volume of the bubbles. And increase the solubility of the CO ₂ molecule. In order to increase the rate at which the CO ₂ molecules collide with the surface of the calcium hydroxide solution, the volume of the bubbles is minimized to reduce the distance between the inner surface of the bubbles and the microdroplets in the bubbles, Reduce the mean free path of CO ₂ molecules in the bubbles and increase the dissolution rate of CO ₂ . The CO ₂ molecule dissolves in the solution, and the reaction between the CO ₂ molecule and the calcium ion (Ca ²⁺ ) and hydroxide ion (OH ⁻ ) in the solution generates a calcium carbonate (CaCO ₃ ) molecule. Precipitates out of solution.

As a result, the CO ₂ scrubber of the present invention separates gaseous CO ₂ from the mixed gas with high selectivity and sequesters CO ₂ from the atmosphere as calcium carbonate for geological times.

The objects and advantages of the objects and advantages the present invention, in order to facilitate the dissolution of CO ₂ molecules to calcium hydroxide solution from the mixed gas stream, the gaseous CO ₂ in the gas mixture, between the calcium hydroxide solution Maximizing the liquid-gas surface area of the calcium hydroxide solution.
Other objects and advantages of the present invention, in order to facilitate the dissolution of CO ₂ Calcium hydroxide molecule solution from the mixed gas stream, the gaseous CO ₂ in the mixed gas stream, between the calcium hydroxide solution To maximize the contact time.

  Another object and advantage of the present invention is to rupture and reform at least some of the bubbles, where the ruptured bubbles form a large number of microdroplets with different radii, each reshaped bubble being a Encapsulating individual volumes, individual numbers of solution microdroplets, and individual volumes of solution vapor.

Another object and advantage of the present invention is to reduce the temperature of the gas mixture in order to promote the dissolution of CO ₂ molecules from the gas mixture stream into the calcium hydroxide solution.

Another object and advantage of the present invention is to increase the ambient pressure on the bubbles of the calcium hydroxide solution and the vapor pressure within the bubbles to facilitate dissolution of the CO ₂ molecules from the mixed gas stream into the calcium hydroxide solution. It is.

Another object and advantage of the present invention is to maximize the contact between the CO ₂ molecules and the solution used to form the bubbles and microdroplets, and the inner surface of each bubble, It is to minimize the mean free path of CO ₂ molecules in the bubbles by reducing the volume of the bubbles so as to shorten the distance between them.

Other objects and advantages of the present invention, in order to maximize the removal of CO ₂ from the gas mixture while minimizing the chance of calcium deposit forms, liquid - minimum mechanical structure while maximizing gas contact area It is to become.

It is a front view of the carbon capture scrubber of the present invention. It is a plan view of a CO ₂ scrubber. It is a front view of the froth generator for CO ₂ scrubber. It is explanatory drawing of formation of a microdroplet and enclosing in a bubble. It is an oblique projection of a precipitation tank. 1 is a plan view of a CCS system having a precipitant treatment. FIG.

FIG. 1 shows an embodiment of the invention comprising a bubble column CO ₂ reactor / scrubber 5 and a method for separating gaseous CO ₂ from a gas mixture. The CO ₂ scrubber maximizes the liquid-gas interface area and exposure time between the gas mixture and calcium hydroxide solution, while at the same time increasing the ambient pressure on the bubbles and increasing the vapor pressure within the bubbles. Designed to maximize the solubility of CO ₂ in calcium hydroxide solution. A CO ₂ scrubber reduces the temperature of the gas and calcium hydroxide solution while simultaneously reducing the volume of bubbles and the mean free path of CO ₂ molecules. The CO ₂ scrubber is also designed to minimize the chance of forming calcium deposits.

Gas Inflow Duct As shown in FIGS. 1 and 2, the gas inflow duct 6 has a plurality of gas outlets 7a, 7b, 7c and 7d arranged in the vicinity of the closed end 6a of the gas inflow duct, together with the reaction chamber 10 Place on top. The plurality of gas outlets 7a to 7d are connected to the plurality of gas inlets 41a, 42a, 43a, and 44a in the plurality of floss generators 41 to 44 and provide fluid communication. A gas stream 9 containing gaseous carbon dioxide flows into the floss generators 41 to 44 via the gas inflow duct 6.

Calcium hydroxide solution To prepare a calcium hydroxide solution suitable for a carbon capture wet scrubber, calcium hydroxide (solid) is dissolved in water. In order to promote dissolution of calcium hydroxide (solid) in the solution, the particle size of the particles is 45 μm or less, and 95% is in the range of 5 to 10 μm. Calcium hydroxide solution is used to form bubbles with about 0.8 grams (0.8 mg / L) of calcium hydroxide per liter of water to make an alkaline solution with a pH of about 11.5. It consists of a mild non-anionic surfactant that reduces the surface tension of the solution.

  The calcium hydroxide solution distribution system (FIGS. 1 and 2) includes a solution supply main pipe 51, a solution pump 52, a solution supply vertical pipe 53, a solution distribution manifold 54, and a plurality of solution distribution pipes 55. A calcium hydroxide solution pump 52 having an inlet and an outlet is located at the top of the dehydration chamber 60. The inlet of the pump 52 is connected to the fluid supply main pipe 51 from the heat exchanger (not shown in FIGS. 1-2) and provides fluid communication. A solution supply longitudinal pipe 53 connects the lower end to the outlet of the solution pump 52 and connects the upper end to the solution delivery manifold 54 at the top of the reaction chamber 10 and provides fluid communication. The solution delivery manifold 54 includes an inlet and a plurality of outlets. The solution delivery manifold 54 is connected to the outlet of the solution delivery vertical pipe 53 at the inlet. Each of the plurality of outlets 55 in the solution delivery manifold 54 is connected to a spray nozzle solution distribution pipe, such as a pipe 56 (see FIG. 3) in the floss generator 42. Each floss generator 41-44 is similarly connected to the manifold 54.

CO ₂ scrubber CO ₂ scrubber Figure 1 has an upper reaction chamber portion 11, the lower reaction chamber portion 12 and a reaction chamber cylinder 10 made of elongated stainless steel having a water portion 15. The precipitation tank 90 is attached to the underwater portion 15 of the reaction chamber cylinder 10. The vertical reaction chamber cylinder 10 having the closed top 14 is connected to a vertical cylinder-shaped exhaust cylinder 70 having an open top by a horizontal, substantially rectangular dehydration chamber 60. A common bottom surface 61 that gradually slopes downward in the dehydration chamber 60, a submerged portion 15 of the reaction chamber 10, and a sloped bottom surface 98 of the precipitation tank 90 continue in the direction of the slurry channel 92 in the precipitation tank 90. An inclined surface is formed.

Floss generators Floss generators 41-44 are located at the top 14 of the reaction chamber 10. A floss generator 42 is shown in FIG. 3 and includes a blower 45, a solution inlet 56 and a solution distribution pipe 56a, a plurality of low pressure (55 psi) spray nozzles 56b, a mesh panel assembly 80 and mesh panel assembly support rails 81 and 82. An outlet 49 is provided.

  The high-pressure blower 45 has components (not shown) including an electric motor, a turbine, a volute (vortex chamber) having a gas inlet and a gas outlet. The electric motor transmits rotational motion to the turbine via mechanical means. The turbine is disposed in a volute and includes blades, paddles, vanes or other mechanical means for converting the rotational motion of the electric motor to increase the pressure of the gas stream 9. The gas inlet in the volute is connected to and in fluid communication with one of the plurality of gas outlets in the gas inlet duct 6. The volute gas outlet is in fluid communication with the gas inlet in the mesh panel assembly 80.

  The solution inlet 56 connects and is in fluid communication with a solution distribution pipe for a plurality of low pressure (55 psi) spray nozzles 56b. Each spray nozzle has a solution inlet and a plurality of solution outlets 56c. The solution inlet is connected to and in fluid communication with the solution distribution pipe 56. The solution outlet 56c is disposed in the vicinity of the closed end of the spray nozzle 56b, and forms a radiation pattern orthogonal to the linear axis of the cylindrical spray nozzle 56b and coaxial. The solution outlet 56 c of the spray nozzle 56 b is disposed close to the first mesh panel 86 at the top of the mesh panel assembly 80. The circular region generated by the radiation pattern of the solution jet from the spray nozzle is orthogonal to the mixed gas flow 9, parallel to the mesh panel 87, and coaxial with the linear axis of the cylindrical spray nozzle 56b.

  The detachable mesh panel assembly 80 is placed on support rails 81 and 82 disposed inside the floss outlet 49 of the floss generator 42, and has a frame 83, an inlet 84, an outlet 85, and a plurality of spacers (not shown). And a plurality of wire mesh panels 87. Further description of the floss generator and mesh panel is described in patent application Ser. No. 11 / 729,253, which is incorporated herein by reference. The mesh panel has a plurality of mesh openings in a range of 2 mm to 25 mm distributed over the bubble generation region of the mesh panel. The mesh panel 87 is disposed on the rectangular frame 83 and positioned so that the mesh opening region is orthogonal to the flow of the mixed gas 9. The sequential mesh panels 87 are arranged in parallel below the preceding mesh panel 87, respectively. The plurality of mesh panels are assembled in a frame 83 that can be detached from the floss generator. The mesh panels 87 are separated from each other by a spacer (not shown) in the range of 5 mm to 0.5 m depending on the application scale and the flow rate of the gas flow 9. The outlet of the mesh panel assembly 80 is internal to and in fluid communication with the floss outlet 49 of the floss generator. The floss generator floss outlet 49 is in fluid communication with the upper portion 11 of the reaction chamber 10.

Reaction chamber 10 includes a closed top 14 that supports an array of floss generators 41-44, an upper portion 11, a lower portion 12 connected to an inlet 62 of a dehydration chamber 60, and an inlet 97 of a precipitation tank 90. A vertical, cylindrical chamber having an underwater portion 15 connected to the. The reaction chamber 10 is provided with a plurality of floss inlets below the floss generators 41 to 44, a vent 19 having a flow control valve 20, and an inclined lower wall 18.

  The adjustable outlet panel 110 is connected to the electric motor 111 and is driven up and down by the electric motor 111. The adjustable panel 110 controls the size of the opening 62 to the dehydration chamber 60. For example, when the panel 110 is activated, the opening 62 can be entirely closed.

  The plurality of inlets are in fluid communication between the reaction chamber 10 and the plurality of outlets in the plurality of floss generators 41-44. The vent 19 is disposed at the top of the reaction chamber and is in fluid communication between the reaction chamber 10 and the atmosphere when the flow regulating valve 20 at the vent 19 is opened. An adjustable opening 62 is located at the bottom of the reaction chamber 10 and is in fluid communication between the reaction chamber 10 and the dehydration chamber 60 when the outlet panel 110 is adjustably opened. The electric motor 111 is connected to an adjustable outlet panel 110 and to a gear mechanism (not shown) that converts the rotational movement of the electric motor 111 into an adjustable vertical movement of the outlet panel 110.

  The surface 99 of the calcium hydroxide solution constitutes the bottom of the lower part 12 of the reaction chamber and the upper boundary of the underwater part 15 of the reaction chamber 10. The walls of the reaction chamber cylinder 10 form a partition wall 95 between the relatively energetic hydrodynamic flow of the underwater portion 15 of the reaction chamber 10 and the relatively gentle hydrodynamic flow of the precipitation tank 90. .

  The bottom 98 of the underwater portion 15 of the reaction chamber 10 is inclined between 30 ° and 45 ° (in the illustrated embodiment) from the bottom of the floss inlet 62 of the dehydration chamber 60 toward the beginning of the slurry channel 92 of the precipitation tank 90. 30 °) and extend downward in the direction of the precipitation tank 90. The plane of the bottom 98 traverses the bottom of the reaction chamber cylinder wall between the dehydration chamber 60 and the intersection of the reaction chamber cylinder wall and the parallel vertical walls 93, 94 of the precipitation tank 90. The plane of the bottom 98 in the underwater portion 15 of the reaction chamber 10 extends below the cylinder wall 95, thereby forming an opening 97 and between the underwater portion 15 of the reaction chamber 10 and the precipitation tank 90. Create fluid communication. The central longitudinal axis of the opening 97 between the underwater portion 15 of the reaction chamber 10 and the precipitation tank 90 is 180 ° from the central longitudinal axis of the solution main outlet 102 of the precipitation tank 90 and the froth outlet 62 of the reaction chamber 10. It is located 180 ° off the center longitudinal axis.

The dehydration chamber 60 is a substantially rectangular chamber and is located between the lower portion 12 of the reaction chamber 10 and the exhaust pipe 70. The chamber 60 has an inclined bottom 61, a low pressure (125 psi) dewatering pump 64, a spray nozzle delivery pipe 65, and a plurality of low pressure (125 psi) spray nozzles 66. The rectangular floss inlet 62 has a longitudinal axis that is longer than the longitudinal axis of the substantially square gas outlet 63. The top of the dehydration chamber 60 is horizontal. The bottom 61 of the dehydration chamber forms a downward (negative) slope of 10 ° to 20 °.

  The dehydration pump 64 is disposed at the top of the dehydration chamber 60. The pump 64 is connected to the solution supply main pipe 51. The pump 64 is connected to a plurality of dehydration spray nozzles 66 in the dehydration chamber 60. Each of the plurality of spray nozzles 66 has a spray outlet at the end of the nozzle in fluid communication with the atmosphere in the dehydration chamber 60.

The exhaust cylinder vertical exhaust cylinder 70 is disposed at the end of the horizontal dehydration chamber 60 and includes an inlet, an outlet, a heat exchange coil, and a vane mist removing device (not shown). The exhaust tube 70 is in fluid communication with the dehydration chamber 60 via the inlet 63. The top of the exhaust tube 70 opens to the atmosphere through the outlet. A heat exchange coil (not shown) from a heat exchanger (not shown) of the solution supply main pipe is attached to the inner upper wall of the exhaust pipe. A vane-type mist removing device (not shown) having a stainless steel vane configured in close contact with an acute angle (echelon) is coaxial and orthogonal to the linear axis of the exhaust stack in its circular region So that it is perpendicular to the gas flow 9.

Precipitation tank As shown in FIG. 5, the parallel vertical flat walls 93, 94 of the precipitation tank 90 are arranged 180 ° apart from each other and between the underwater portion 15 of the reaction chamber 10 and the precipitation tank 90. Attached to the reaction chamber cylinder at a 90 ° offset from the longitudinal central axis of outlet 97. The inclined lower parts 93a, 94a of the two parallel walls 93, 94 in the settling tank are each at an angle between 30 ° and 45 ° (45 ° in the illustrated embodiment) towards the slurry channel 92. Tilt. A coarse sediment slurry collection channel 92 is formed at the bottom of the sedimentation tank 90 in parallel with the bottom of the inclined parallel walls 93a, 94a. The slurry discharge port 103 is disposed in the vicinity of the bottom of the vertical flat end wall 91 of the precipitation tank 90 on the linear central vertical axis. The slurry discharge port 103 is connected to a slurry discharge pipe (not shown) and is in fluid communication. The solution flow main outlet 102 is disposed on the central vertical axis in the vicinity of the upper end of the vertical flat end wall 91 of the precipitation tank 90. The top of the precipitation tank 90 is opened to the atmosphere.

Operation The present invention includes a CO ₂ scrubber and a method for separating gaseous CO ₂ as calcium carbonate from a gas mixture. The CO ₂ scrubber incorporates a calcium hydroxide solution to react with dissolved CO ₂ with high selectivity to precipitate calcium carbonate from the solution and minimize the chance of calcium deposits forming, Designed to maximize the absorption of CO _{2 into} the solution.

The plurality of mesh openings in each of the plurality of mesh panels 87 of the mesh panel assembly 80 (see FIG. 3) is saturated with a calcium hydroxide solution containing calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ ). A mixed gas stream 9 containing gaseous CO ₂ is forced to pass through the saturated mesh assembly 80 to form an aqueous floss, where the calcium hydroxide bubbles in the floss are filled with an individual volume of the mixed gas. Have a volume. At least some of the bubbles rupture and reform, and the ruptured bubbles form a large number of microdroplets 31 with various radii, including Kelvin-limited microdroplets (see FIG. 3), each reshaped bubble being a gas Enclose the individual volume of stream 9, the individual number of microdroplets 31 of solution and the individual volume of solution vapor. The size of the bubbles formed is limited by limiting the opening size of the mesh panel 87 and thereby forming an infinite number of uniform small bubbles 32, and thus the CO ₂ molecules, the microdroplets 31, and the innumerable numbers. Maximize contact between the inner and outer surfaces of the small bubbles 32.

  The Kelvin limit of a microdroplet is the limit of the microdroplet radius at ambient conditions, where the microdroplet is subject to irreversible evaporation caused by vapor loss due to the extreme curvature of the surface of the microdroplet. Start. Calcium hydroxide microdroplets 31 having a wide distribution of microdroplet radii, including Kelvin-limited microdroplets, are included in reshaped bubbles 32 (see FIG. 3).

As the Kelvin-limited microdroplets evaporate, sensible heat is converted into latent heat to separate the calcium hydroxide solution molecules as gas, thereby cooling the gas in the bubbles. Upon evaporation, the water in the calcium hydroxide solution increases its volume by 1600 times, thereby increasing the vapor pressure in the bubbles. The gas stream 9 is carried down through the reaction chamber 10 by the bubble column 30 to increase the reaction time between the gas stream 9 and the myriad small bubbles 32 and to increase the ambient pressure on the bubbles. As a result, the bubble size is reduced and the solubility of the CO ₂ molecule is increased. The mean free path of the CO ₂ molecules in the bubble is minimized by reducing the bubble volume to reduce the distance between the inner surface of the bubble and the microdroplet 31 in the bubble 32, so that CO ₂ The rate at which molecules collide with the surface of the calcium hydroxide solution increases. The increased rate of collision between the CO ₂ molecule and the solution increases the dissolution rate of CO ₂ . As a result, the CO ₂ scrubber of the present invention maximizes the dissolution of gaseous CO ₂ into the calcium hydroxide solution. The CO ₂ molecules brought into the solution generate calcium carbonate (CaCO ₃ ) molecules by the reaction of the CO ₂ molecules with calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ ) in the solution. Calcium precipitates from the solution.

Gas inlet duct gas inlet duct 6, a mixed gas stream 9 containing gaseous CO _2, from a plurality of gas outlet 7a~7d disposed near the closed end 6a of the gas inlet duct 6, a large number of froth generator The gas is fed to a plurality of gas inlets 41a, 42a, 43a, 44a in 41-44.

Calcium hydroxide solution Calcium hydroxide (solid) is dissolved in water to prepare a suitable calcium hydroxide solution for a carbon capture wet scrubber. In order to promote dissolution of calcium hydroxide (solid) in the solution, the particle size of the particles is 45 μm or less and 95% is in the range of 5 to 10 μm. Calcium hydroxide dissolves calcium hydroxide in water at a concentration of 0.8 g / L together with a mild non-anionic surfactant to reduce the surface tension of the solution to form calcium hydroxide bubbles. Increase the alkalinity of the calcium hydroxide solution to about 11.5. The concentration of surfactant determines the lifetime of the bubbles. The concentration of the surfactant lasts long enough for most of the bubbles to enclose the gas mixture 9 from the floss generators 41-44 to the dehydration chamber 60, but fires from the spray nozzle 66 in the dehydration chamber 60. It adjusts so that it may dehydrate by the collision of a droplet.

  The calcium hydroxide solution is cooled to a relatively low temperature of at least 20 ° C., which is lower than the relatively high temperature of the mixed gas stream 9, and from the calcium hydroxide solution pump 52 via the solution supply vertical pipe 53, Pump to solution delivery manifold 54 at top 14 of reaction chamber 10. A solution delivery manifold 54 distributes the calcium hydroxide solution to a plurality of floss generators 41-44 at the top 14 of the reaction chamber 10. The calcium hydroxide solution is distributed from the solution distribution manifold 54 to the solution distribution pipe 55. The flow of the solution to the floss generators 41 to 44 is adjusted by the flow rate adjustment valve 58 of the solution distribution pipe 55. Solution flow to the floss generators 41-44 can be interrupted to remove and replace the mesh panel assembly 80 during routine maintenance.

CO ₂ scrubber CO ₂ scrubber present invention, while minimizing the mechanical structure that provides an opportunity for calcium deposits to form, designed to maximize the dissolution of CO ₂ into calcium hydroxide solution. Calcium hydroxide solution is cooled before the CO ₂ scrubber in order to increase the solubility of CO _2. The CO ₂ scrubber encloses a mixed gas stream 9 containing gaseous CO _{2 in} bubbles formed of an aqueous floss of a calcium hydroxide solution together with micro droplets 31 and vapor of the calcium hydroxide solution. The relatively hot gas in bubble 32 evaporates the smallest microdroplets and converts sensible heat into latent heat, thereby cooling the gas in bubble 32. The evaporated microdroplet 31 expands its volume to 1600 times the volume of the liquid, thereby increasing the vapor pressure in the bubble 32. Bubble column 30 flows down through reaction chamber 10, increasing the ambient pressure on the bubble, reducing the bubble volume, and increasing the vapor pressure within bubble 32. The gas containing gaseous CO ₂ contained in the bubbles is diffused through the common bubble wall due to the pressure difference between adjacent bubbles of different volumes. As the volume of the bubbles decreases, the mean free path of the CO ₂ molecules decreases, resulting in an increase in the rate at which gaseous CO ₂ dissolves in the calcium hydroxide solution. Thereby, the CO ₂ scrubber maximizes the dissolution of gaseous CO _{2 in} the calcium hydroxide solution. The dissolved CO ₂ reacts with calcium ions and hydroxide ions in the solution, and calcium carbonate precipitates from the solution.

A plateau boundary (intersection of intermediate walls between adjacent bubbles of aqueous floss) and a plateau boundary contact (of three or more plateau boundaries), in which the bubble column 30 constitutes a complex interconnected fluid structure that flows with the bubble column 30 An aqueous floss matrix at the intersection). The aqueous floss matrix exponentially increases the liquid-gas interface area of the calcium hydroxide solution. As the bubble column 30 is formed, the foam matrix constantly replenishes itself and transfers the precipitate through the reaction chamber 10 to the calcium hydroxide solution tank at the bottom of the CO ₂ scrubber. The surface 99 of the calcium hydroxide solution constitutes the top of the underwater portion 15 of the reaction chamber 10 at the bottom of the lower reaction chamber 12 and forms the top of the underwater portion of the dehydration chamber 60 at the bottom of the dehydration chamber 60. Precipitates suspended in the froth matrix of the bubble column 30 are deposited directly in the calcium hydroxide solution at the bottom of the reaction chamber 10 and dehydration chamber 60, minimizing the opportunity for calcium deposits to form. The hydrodynamic flow and the slope of the bottoms 61, 98 in the dewatering chamber 60 and the underwater portion 15 of the reaction chamber 10 transfer the sediment to the sedimentation tank 90. Accordingly, the CO ₂ scrubber of the present invention is designed to minimize the chance of calcium deposit formation.

The mixed gas stream 9 containing the floss generator gaseous CO ₂ flows from the gas inflow duct 6 into a plurality of floss generators 41 to 44 arranged at the top 14 of the vertical reaction chamber 10. The mixed gas stream 9 flows into the floss generators 41 to 44 from the inlet of the volute (vortex chamber). The shape of the turbine blades and volute increases the pressure of the gas flow, which allows the gas mixture and calcium hydroxide solution to be forced through the mesh panel assembly 80.

  The calcium hydroxide solution is distributed to the spray nozzle 56 b through the solution inlet of the spray nozzle distribution pipe 55 of the floss generators 41 to 44. The spray nozzle distribution pipe 55 supplies a solution to the plurality of low pressure spray nozzles 56b. The low pressure (55 psi) spray nozzle 56b can spray the solution around the spray nozzle in a radial pattern via the spray nozzle outlet 56c and saturate the mesh panel 87 with the calcium hydroxide solution.

The mesh panel assembly 80 in each froth generator 41-44 is saturated with a calcium hydroxide solution containing calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ ) that react with gaseous CO ₂ . A mixed gas stream 9 having gaseous CO ₂ is forced from the outlet of the volute to the inlet 84 of the mesh panel assembly 80 at a relatively high pressure. The mixed gas 9 is passed through the mesh opening of the saturated mesh panel assembly 80 to form the bubble column 30.

The size of bubbles formed by passing the mixed gas stream 9 and the calcium hydroxide solution through the mesh panel 87 is proportional to the opening size of the mesh panel 87. The bubble size formed is limited by restricting the opening size of the mesh panel 87 to form an infinite number of uniform small bubbles 32, whereby CO ₂ molecules, solution microdroplets 31, Maximize contact between the surface and the outer surface. The bubbles 32 are forced out of the mesh panel 87 via the outlet 85 of the mesh panel assembly 80, then exhausted through the floss generator outlet 49 and forced out into the floss inlet at the top 14 of the reaction chamber 10. .

The gravitational acceleration reduces the energy required to force the mixed gas stream 9 and the aqueous calcium hydroxide solution to the mesh panel assembly 80. As the gas stream 9 passes the solution through the saturated mesh panels 87 of the floss generators 41-44, bubbles are created. As the mixed gas, calcium hydroxide solution droplet 31, bubble 32, microdroplet and vapor pass through the mesh opening and sequentially through the mesh panel 87 of the mesh panel assembly 80, the bubble is formed, ruptured and regenerated. It is formed. A gas mixture containing gaseous CO ₂ , calcium hydroxide solution microdroplets 31 and vapor are contained within the reformed bubbles 32. The microdroplet floating in the gas in the bubble is formed by the liquid fragment from the ruptured bubble wall and the droplet crushed into the microdroplet by the mixed gas flow 9, and the solution and the mixed gas are the next mesh. It is contained in the second bubble reshaped by being passed through the panel 87. Bubbles 32 are released downward into the reaction chamber 10.

Reaction chamber Reaction chamber 10 is designed to maximize the solubility of CO _{2 in} calcium hydroxide solution and minimize the chance of calcium deposit formation. The solubility of CO ₂ is proportional to pressure and inversely proportional to temperature.

  The mixed gas is enclosed in the bubbles of the calcium hydroxide solution, increasing the contact time between the mixed gas 9 and the countless bubbles 32 of the calcium hydroxide solution. The relatively hot and dry mixed gas stream 9 evaporates the Kelvin critical microdroplets in the bubbles, increases the vapor pressure in the bubbles, and cools the gas in the bubbles. The cooled calcium hydroxide solution that produces the liquid floss matrix cools the gas mixture in the bubbles. When the gas in the bubble is cooled, the first evaporated liquid is condensed and returned to the liquid. The condensed vapor has an affinity for similar liquid surfaces and condenses on the microdroplets and bubble walls floating in the air within the bubbles.

  When the reaction chamber 10 is filled with the bubbles 32, the flow rate adjusting valve 20 of the vent 19 is opened, and the air in the reaction chamber 10 is exhausted from the vent 19 to the atmosphere. When the reaction chamber 10 is filled with bubbles up to a predetermined volume, the flow rate adjustment valve 20 of the vent 19 is closed, and fluid communication between the reaction chamber 10 and the atmosphere via the vent 19 is blocked.

  As shown in FIG. 1, the calcium hydroxide bubble column 30 forms a calcium hydroxide froth matrix that fills the diameter portion of the reaction chamber 10 to a predetermined height, and also forms a fluid plug in the reaction chamber 10 so that the gas is bubbled. Prevent bypassing column 30 or allow gas to pass through bubble column 30. The floss outlet 62 is opened by raising the adjustable outlet panel 110 using an electric motor 111 and a gear mechanism (not shown). Bubble column 30 begins to flow from reaction chamber 10 to dehydration chamber 60 due to gravitational acceleration and relatively high air pressure from blower 45 of floss generators 41-44. The inclined lower wall 18 of the reaction chamber 10 turns the flow of the bubble column 30 from the floss outlet 62 on the opposite side of the reaction chamber 10 toward the floss outlet 62.

  During normal operation, the flow control valve 20 of the vent 19 is closed, preventing air from the atmosphere from flowing into the reaction chamber 10 through the vent 19. The relatively low air pressure at the top of the reaction chamber 10 and the froth volume in the reaction chamber 10 are maintained at a predetermined level to maintain a constant vertical pressure gradient in the reaction chamber 10, which is maintained by the floss generator 41. The bubble flow rate from ˜44 is balanced with the bubble flow rate discharged from the floss outlet 62 at the bottom of the reaction chamber 10.

The solubility of CO ₂ is proportional to the pressure. The flow of the bubble column 30 in the reaction chamber 10 descends from the froth generators 41 to 44 at the top of the reaction chamber 10 toward the dehydration chamber 60 at the bottom of the reaction chamber 10, and the weight of the bubble column 30 above causes the bubbles to surround the bubble. Increase pressure. As shown in FIG. 1, the bubbles become smaller as they flow down the reaction chamber 10. Increasing the ambient pressure reduces the volume in the bubble where the gas mixture is available and increases the vapor pressure in the bubble, increasing the solubility of gaseous CO _{2 in} the calcium hydroxide solution. As the volume in the bubble available to the gas mixture decreases, the distance that the CO ₂ molecules must travel while colliding with the surface of the solution decreases proportionally and must move while the molecules collide. The mean free path that must be lost and the surface of the solution decrease, and the CO ₂ concentration in the solution increases rapidly.

The vapor pressure in the bubble is proportional to the bubble wall tension and inversely proportional to the bubble radius (Laplace's law). Therefore, if the bubble is made smaller, the vapor pressure in the bubble becomes higher. The mixed gas enclosed in the froth bubbles diffuses through the common bubble wall due to the pressure difference between adjacent bubbles of different volumes. A small bubble with a relatively high vapor pressure diffuses that volume of a gas mixture containing gaseous CO ₂ through a common bubble wall into a large bubble with a low vapor pressure.

The dissolved CO ₂ molecules react with calcium ions and hydroxide ions in the solution to generate calcium carbonate molecules, and calcium carbonate is precipitated from the solution.

  The liquid level 99 of the calcium hydroxide solution facilitates the flow of the bubble column 30 from the reaction chamber 10 to the dehydration chamber 60 and does not provide an opportunity for calcium deposits to form. When the bubble column 30 flows out of the reaction chamber 10 into the dehydration chamber 60 due to the weight of the bubble column 30, a relatively low air pressure is generated at the top of the reaction chamber 10.

  The relatively low air pressure at the top of the reaction chamber 10 reduces the energy required by the blower 45 to force the mixed gas stream 9 and calcium hydroxide solution to pass through the mesh panel assembly 80. The relatively low air pressure at the top of the reaction chamber 10 and the volume of froth in the reaction chamber 10 are determined by the flow rate of bubbles from the floss generators 41-44 and the discharge rate of bubbles from the floss outlet 62 at the bottom of the reaction chamber 10. It is controlled by balancing.

  The underwater portion 15 of the reaction chamber 10 is positioned below the reaction chamber 10 to minimize the chance of calcium deposits forming. A 30 ° inclined bottom 98 extends below the reaction chamber cylinder 10 and allows sediment to flow downward into the sedimentation tank 90.

  The total flow rate and hydrodynamic energy of the solution from the froth matrix in the reaction chamber, the spray nozzle 66 and the dehydrated bubbles, and in the dehydration chamber 60 pass through the underwater portion 15 of the reaction chamber 10. The volume of the calcium hydroxide solution in the underwater portion 15 of the reaction chamber 10 is larger than the underwater portion of the dehydration chamber 60 and smaller than the volume of the solution in the precipitation tank 90 to maintain a heavy sediment in a floating state. The energy available to the solution is gradually reduced. The hydrodynamic energy state of the calcium hydroxide solution through the underwater portion 15 of the reaction chamber 10 keeps everything except the heaviest precipitate in suspension. Most of the sediment is transported to the sedimentation tank 90 in a floating state. The heaviest precipitate that settles out of solution in the reaction chamber 10 agglomerates into a very loosely solidified mass on the sloped bottom 98 due to local instability, along the sloped bottom 98 of the precipitation tank 90. Settling towards the bottom.

When the dehydration chamber bubble column flows into the dehydration chamber 60, the bubbles are dehydrated by collision of the fired spray droplets from the plurality of spray nozzles 66 disposed at the top of the dehydration chamber 60 with the bubble walls. The gas released from the bubbles flows into the exhaust pipe 70 from the dehydration chamber 60. The precipitate contained in the bubbles accumulates in the calcium hydroxide solution at the bottom of the dehydration chamber 60, minimizing the opportunity for calcium deposition to occur. The solution surface in the dehydration chamber forms a common bottom surface with the reaction chamber 10, which facilitates the flow of bubbles from the reaction chamber 10 to the dehydration chamber 60.

The main flow of solution through the CO ₂ scrubber is from the floss generators 41-44 at the top of the reaction chamber 10 and the spray nozzle 66 in the dehydration chamber 60 to the solution at the bottom of the dehydration chamber 60 and the underwater portion 15 of the reaction chamber 10. Inflow. The hydrodynamic energy from the dehydrated bubbles and the flow of solution from the spray nozzle 66 at the top of the dehydration chamber 60 is concentrated into a relatively small volume of calcium hydroxide solution in the underwater portion of the dehydration chamber 60. The relatively large energy transfers a heavy precipitate that can precipitate from the solution under less energetic hydrodynamic conditions to the underwater portion 15 of the reaction chamber 10. Production of aqueous froth, drainage of aqueous froth matrix in the reaction chamber 10, angle of 10 ° to 20 ° (10 ° in the figure) of the inclined bottom 61 of the underwater portion of the dehydration chamber 60, of the underwater portion 15 of the reaction chamber 10 The hydrodynamic energy of the solution flow in the CO ₂ scrubber from the 30 ° -45 ° angle (30 ° in the illustration) of the bottom 98 and the precipitation tank 90 from the underwater portion of the dehydration chamber 60 to the underwater portion 15 of the reaction chamber 10. Then, the precipitate is transferred into the precipitation tank 90 and settled.

Precipitation tank The reduced hydrodynamic energy of the precipitation tank 90 separates the heavy calcium carbonate precipitate from the fine precipitate in suspension. The heavy precipitate precipitates from the suspension by the deposition process and deposits in the slurry channel 92 at the bottom of the precipitation tank 90. A lesser weight precipitate remains in the suspension. The precipitate precipitated from the solution in the precipitation tank 90 slides or falls along the 45 ° inclined side surfaces of the lower portions 93a, 94a of the parallel walls 93, 94 of the precipitation tank 90, not directly above the slurry channel 92. . The hydrostatic pressure of the precipitation tank 90 pushes the coarse sediment slurry from the coarse sediment slurry outlet 103. The lesser weight precipitate remains in the suspension flowing from the precipitation tank 90 through the solution flow main outlet 102.

The gas released from the bubbles ruptured in the exhaust tube dewatering chamber 60 flows into the exhaust tube 70. At the relatively increased diameter of the exhaust stack 70, the energy available to the airflow to carry the microdroplets is reduced. The heavy microdroplets associated with the gas stream 9 are removed by gravity separation. Smaller liquid droplets are removed from the gas stream 9 by inertial impact on vanes knitted into close trapezoids with an acute angle of a mist remover located at the top of the exhaust stack 70. The mixed gas stream 9 from which at least a part of the gaseous CO ₂ has been cleaned (purified) is discharged into the atmosphere.

The present invention for operating theory CCS includes a method for separating gaseous CO ₂ from a CO ₂ scrubber and gas mixture. The CO ₂ scrubber is designed to maximize gaseous CO ₂ absorption into the solution. A CO ₂ scrubber incorporates a calcium hydroxide solution to react with dissolved CO ₂ with high selectivity and precipitates calcium carbonate from the solution.

In order to increase the solubility of CO ₂ , the solution is cooled and the ambient pressure on the bubbles and the vapor pressure within the bubbles are increased. Liquid between the gaseous CO ₂ and calcium hydroxide solution - gas ratio and exposure time, maximized by encapsulating the gas flows and microdroplets countless calcium hydroxide uniform small bubble in the calcium hydroxide solution To do. The bubble column flows down in the reaction chamber and incorporates gravitational acceleration to reduce the energy required to pass the gas flow through the saturated mesh panel to create the bubble column. The ambient pressure for the bubble increases as the bubble flows downward in the reaction chamber, increasing the bubble wall tension and then increasing the vapor pressure within the bubble. Gases contained within the bubbles and containing gaseous CO ₂ diffuse through the common bubble wall due to pressure differences between adjacent bubbles of different volumes. A gas that diffuses from a relatively small bubble having a relatively high vapor pressure to a relatively large bubble having a relatively low vapor pressure forces CO ₂ to dissolve in the solution.
Condensation reduces the volume of the bubbles and increases the diameter of the calcium hydroxide microdroplets suspended in the air in the bubbles maximizes the liquid-gas contact and allows the CO ₂ molecules to move into the calcium hydroxide solution. Shorten the mean free path to travel before colliding with the surface, thereby maximizing the solubility and absorption rate of CO ₂ , respectively. The dissolved CO ₂ becomes calcium carbonate precipitate and is sequestered from the atmosphere for the geological era. The calcium carbonate precipitate is processed and sold as an admixture of inorganic fillers, acidic soil neutralizers, slope stabilizers, fluidizers and Portland cement. Next to water, concrete is the most essential commodity used by humans. In a highly purified form, precipitated calcium carbonate (PCC) is used in the industrial manufacturing process of paper, plastic, food and pharmaceutical. The sale of CO ₂ recovered as a calcium carbonate precipitate reduces at least part of the cost of CCS.

Calcium carbonate plants favor geological locations where limestone deposits, natural gas deposits, natural gas distribution pipelines can be used, and / or geological sequestration of CO ₂ released during the production of calcium oxide Install in a suitable place. Limestone is heated in a lime kiln to expel CO ₂ and form calcium oxide. CO ₂ gas released during the production of calcium oxide is in situ in the secondary recovery of crude oil (EOR), advanced coal seam methane recovery (EMCR), salinity aquifers, in unmined coal seams or under cap rock structures Isolate geologically for carbonation. Calcium oxide, which is produced with environmental responsibility, is transferred from the production site to the CCS site. In order to remove CO ₂ directly from the atmosphere, the CCS operation can be installed at the same geological advantage as the calcium carbonate plant.

  At the CCS site, calcium hydroxide is neutralized with water to produce calcium hydroxide (solid). Calcium hydroxide is dissolved in water to prepare a calcium hydroxide solution.

A large amount of heat is released when preparing calcium hydroxide and sodium hydroxide solutions.
In the case of calcium hydroxide, the reaction is as follows.
CaO + H ₂ O → Ca (OH) _{2 (aq)} + heat The heat released in the case of calcium hydroxide is determined as 65.3 kJ / mol based on the change in enthalpy.
In the case of sodium hydroxide, the reaction is as follows.
NaOH + H ₂ O → NaOH _(aq) + heat The heat released in the case of sodium hydroxide is determined as 44.5 kJ / mol based on the change in enthalpy.

  The solubility of calcium hydroxide and sodium hydroxide in 20 ° C. water is 0.165 g / 100 ml and 111 g / 100 ml, respectively. The relatively low solubility of calcium hydroxide does not prevent the pH (> 10) required for rapid absorption of carbon dioxide.

Due to kinetic considerations, special care must be taken when using calcium hydroxide for CO ₂ capture. As discussed by Brinkman et al., The reaction rate has a strong dependence on pH. There are two mechanisms for bicarbonate formation. In one case, carbonic acid is first formed,
CO _{2 (aq)} + H ₂ O → H ₂ CO _{3 (aq)}
Thereafter, the decomposition H ₂ CO ₃ + H ₂ O → H ₃ O ⁺ + HCO ₃ ⁻
Followed.
The carbonic acid formation process is a relatively slow reaction in the absence of a catalyst.

At pH> 8, the second mechanism is CO _{2 (aq)} + OH ⁻ → HCO ₃ ⁻ with a fast reaction rate.
including.

Both mechanisms then proceed to produce calcium carbonate through the following steps.
HCO ₃ ⁻ + H ₂ O → H ₃ O ⁺ + CO ₃ ⁻
Ca ²⁺ + CO ₃ ⁻ → CaCO ₃

At pH> 10, the second mechanism is advantageous because high pH is optimal for CO ₂ capture using calcium hydroxide solution.

Therefore, in the CO ₂ scrubber of the present invention, the alkalinity operating range of the calcium hydroxide solution is above pH 8.0, but optimal so that the fast reaction from dissolved CO ₂ to carbonic acid is dominant. The operating range is above pH 10.0. In a calcium hydroxide solution, 0.8 grams of calcium hydroxide dissolved in 1 liter of water (0.8 g / L) creates a solution with a pH of about 11.5. When CO ₂ molecules bind to calcium and hydroxide ions, the pH of the solution decreases. CO ₂ absorption capacity of the solution is proportional to the pH of the solution. The optimal alkalinity range of the calcium hydroxide solution to remove gaseous CO ₂ directly from the atmosphere to ensure that fast reaction rates dominate the reaction with relatively low concentrations of atmospheric CO ₂ . The pH is 11.0 to 11.5. The post-treatment gas and the post-combustion exhaust gas can have a high gaseous CO ₂ concentration and the ability to continue to absorb CO ₂ with a fast reaction (pH> 10) while the calcium hydroxide solution is present in the reaction chamber. May require high initial alkalinity to have

Operation of the CO ₂ scrubber of the present invention in the optimal alkalinity range results in scaling for all exposed portions. The Langeria saturation index (LSI) is probably the most widely used indicator of the scale potential of water. This is an equilibrium index and corresponds only to the thermodynamic driving force of calcium carbonate scale formation and growth. This represents a driving force for scale formation and growth from a pH perspective as an excellent variable. In order to calculate LSI, alkalinity (mg / L, CaCO ₃ equivalent), calcium hardness (mg / L Ca ²⁺ , CaCO ₃ equivalent), total evaporation residue (mg / L TDS), actual pH and water temperature ( ℃) need to know. If the TDS is unknown but the conductivity is known, one mg / L TDS can be estimated. LSI is
LSI = pH-pH _S
Can be defined as Where pH is the measured water pH, pH _S is the saturated pH of calcite or calcium carbonate, and
pH _S = (9.3 + A + B)-(C + D)
Defined by Where
A = (Log ₁₀ [TDS] -1) / 10
B = −13.12 × Log ₁₀ (° C. + 273) +34.55
C = Log ₁₀ [Ca ²⁺ , CaCO ₃ conversion] −0.4
D = Log ₁₀ [Alkalinity, CaCO ₃ equivalent]
It is.

The CO ₂ scrubber of the present invention is a CO ₂ scrubber machine because the alkalinity is kept high to enhance the transfer of CO ₂ molecules from the mixed gas to the calcium carbonate precipitate in suspension through the solution phase. Designed to minimize the chance of calcium deposits forming on the structural structure. The mesh panel assembly is the only place in the CO ₂ scrubber where the mixed gas containing gaseous CO ₂ and the calcium hydroxide solution come together in a complex mechanical structure. The removable mesh panel assembly is designed so that it can be removed and replaced during routine maintenance. The mesh panel is cleaned with weak acid, reassembled and replaced during the next scheduled periodic maintenance. The CO ₂ scrubber has a minimal mechanical structure from the top of the reaction chamber to the precipitation tank to minimize the chance of calcium deposit formation. The surface of the calcium hydroxide solution constitutes the surface of the underwater portion of the reaction chamber at the bottom of the reaction chamber and forms the surface of the underwater portion of the dehydration tank at the bottom of the dehydration chamber. Precipitates floating in the froth matrix of the bubble column deposit directly into the calcium hydroxide solution at the bottom of the reaction and dehydration chambers, minimizing the chance of calcium deposits forming. The hydrodynamic flow, as well as the slope of the bottom of the submerged part in the dehydration chamber and the submerged part of the reaction chamber, transfers the sediment to the sedimentation tank. Thus, the CO ₂ scrubber of the present invention is designed to minimize the chance of calcium deposit formation.

Gravitational acceleration is incorporated to reduce the energy required by the floss generator to pass the mixed gas stream and calcium hydroxide solution through the mesh panel. In order to incorporate gravitational acceleration and allow the gas mixture and calcium hydroxide solution to pass partially through the mesh panel, the saturated mesh panel of the floss generator is positioned with its bubble generation region orthogonal to the linear axis of the reaction chamber. When the reaction chamber is filled with bubbles, potential energy is stored in the bubble column. As the bubble column flows from the reaction chamber, this potential energy is partially converted into the kinetic energy of the bubble column flowing from the reaction chamber and partially into the gas mixture and solution drawn through the mesh panel of the floss generator. And the aqueous froth is partially drawn into the reaction chamber by low pressure. As a result, gravitational acceleration is incorporated and the energy required by the CO ₂ scrubber of the present invention is reduced.

In the CO ₂ scrubber of the present invention, the continuous flow of gas mixture containing gaseous CO ₂ and the continuous flow of calcium hydroxide solution together provide continuous carbon capture and sequestration. The CO ₂ scrubber is designed to maximize the mass transfer of gaseous CO ₂ from the gas mixture to the calcium hydroxide solution.

Mass transfer between the CO ₂ molecules in the gas stream and the calcium hydroxide solution is proportional to the solubility of CO ₂ . The solubility of CO ₂ depends on several factors, for example, a liquid - gas surface area, CO ₂ gas and exposure time between the calcium hydroxide solution, CO ₂ that relate the temperature of the liquid and the CO ₂ gas, to the liquid pressure of the liquid It is affected by the vapor pressure, the vapor pressure difference between adjacent froth bubbles, and the free mean path that the CO ₂ molecules must travel in the event of a collision.

  The liquid-gas surface area of the calcium hydroxide solution increases exponentially by enclosing the mixed gas stream within the bubbles of the calcium hydroxide solution. The calcium hydroxide solution is forced through a mesh panel assembly in a plurality of floss generators at the top of the reaction chamber. As the air bubbles travel through each mesh panel of the mesh panel assembly, some of the air bubbles rupture and re-form. Calcium hydroxide microdroplets with broad radius distribution, formed by splitting by aerodynamic friction with a ruptured bubble wall and a large droplet gas stream, and calcium hydroxide vapor travel through the mesh panel In between, it is contained within the bubble as part of the bubble reformation. The microdroplet introduced into the bubble by the bursting of the bubble and the breakup of the droplet in the floss generator includes a Kelvin limit microdroplet. The Kelvin limit of a microdroplet is the diameter at which the microdroplet undergoes irreversible evaporation due to vapor loss due to the ultimate curvature of the microdroplet surface. A relatively warm and dry mixed gas stream evaporates the Kelvin critical microdroplets in the bubbles and increases the vapor pressure in the bubbles.

  The moist inner and outer surfaces of the bubbles, as well as the surface area of the microdroplets, provide the primary region for the gas-molecule phase transition between the gas stream and the calcium hydroxide solution. The bubble size is limited by the size of the mesh panel opening. The mixed gas stream, the calcium hydroxide solution and the small openings in the mesh panel produce a myriad of uniform small bubbles.

The exposure time between the CO ₂ in the gas stream and the calcium hydroxide solution is maximized by the inclusion of a gas mixture containing gaseous CO ₂ within the bubbles of the calcium hydroxide solution. A separate volume of the gas mixture is contained in the bubbles of calcium hydroxide solution from the froth generator at the top of the reaction chamber until the bubbles are ruptured by spraying droplets in the dehydration chamber.

The solubility of CO ₂ is inversely proportional to temperature. As bubbles are formed, individual volumes of the relatively hot and dry gas mixture enclosed within the bubbles evaporate the Kelvin critical droplets. When the water in the calcium hydroxide solution evaporates, its volume expands 1600 times. The sensible heat of the relatively hot gas is converted to the latent heat required to separate the calcium hydroxide solution molecules from a liquid physical state to a gaseous physical state. Furthermore, in order to increase the solubility of CO _2, the heat exchanger cools the calcium hydroxide solution before the solution is introduced into the froth generator. The warm and dry gas is cooled in the bubbles by a cooled calcium hydroxide solution that constitutes the froth matrix; the cross-cell walls and cross-boundary contacts in the adjacent cells of the bubble column. As the gas mixture in the bubble is cooled, the condensed vapor has an affinity for a similar liquid surface and increases the mass and diameter of the microdroplets in the air within the bubble.

The solubility of CO ₂ is proportional to the pressure. The vapor pressure within each bubble is increased to increase the solubility of CO _{2 in} the calcium hydroxide solution. If the vapor pressure of the gas above the liquid is higher than the hydrostatic pressure of the liquid, more molecules will be absorbed by the liquid than will escape from the liquid, and the concentration of the gas in the liquid will increase with time. Kelvin-limited microdroplets are evaporated by a relatively hot and dry gas mixture in the bubbles. The water in the calcium hydroxide solution expands its volume by 1600 times in the bubbles and increases the vapor pressure in the bubbles.

The longitudinal (vertical) floss column creates a longitudinal (vertical) pressure gradient that increases as the bubbles are carried downwardly by the bubble column flow. The increased pressure reduces the bubble radius and increases the vapor pressure within the bubble. In addition, Pierre Laplace (1749-1847) taught that the vapor pressure in a bubble is proportional to the surface tension of the bubble wall and inversely proportional to the radius (Laplace's law for bubbles). When the bubble radius is reduced, the vapor pressure in the bubble increases. As the bubble diameter decreases due to an increase in ambient pressure, the vapor pressure within the bubble increases. The inherent advantage of using an aqueous floss of calcium hydroxide for the separation of CO ₂ from the gas mixture is that the pressure difference between the foam walls drives the diffusion of the gas through the foam walls (roughening of the foam structure). Is caused). Small bubbles with high vapor pressure diffuse the volume of gas through the bubble wall into large bubbles. The CO ₂ scrubber of the present invention has advantages over the prior art by incorporating a further increase in vapor pressure within the bubble and diffusion of gas through the bubble wall, as illustrated by Laplace's law. The vapor pressure within each bubble is increased to increase the solubility of CO _{2 in} the calcium hydroxide solution.

The bubble radius, which has been reduced by the increase in ambient pressure, combined with the surface area of the microdroplets in the bubble growing by condensation, reduces the volume of gas available in the bubble, resulting in CO ₂ molecules in the event of a collision. Shorten the mean free path that must travel. As the mean free path of the molecule decreases, the collision rate between the CO ₂ molecule and the surface of the calcium hydroxide solution increases, increasing the dissolution rate of CO _{2 in} the calcium hydroxide solution.

CO ₂ is water soluble and dissolves in aqueous solution up to the saturation point. In the aqueous calcium hydroxide solution, the dissolved CO ₂ reacts with calcium ions and hydroxide ions in the solution to produce insoluble calcium carbonate. Calcium carbonate precipitates from the solution into the suspension. When dissolved CO ₂ reacts with calcium ions and hydroxide ions in the solution, the dissolved CO ₂ is removed from the solution, allowing more gaseous CO ₂ to dissolve in the calcium hydroxide solution. . Dissolution of CO _2, the reaction of the CO ₂ molecule, calcium ions and hydroxide ions in the solution, and precipitation of calcium carbonate from the solution, CO ₂ prevents to saturate the solution. The CO ₂ molecules transfer from the gas stream through the liquid phase to a solid calcium carbonate precipitate in suspension and allow continuous dissolution of gaseous CO _{2 in} the calcium hydroxide solution.

Thus, the CO ₂ scrubber of the present invention maximizes the solubility of CO _{2 in} calcium hydroxide solution in order to maximize the capture of gaseous CO ₂ from the gas mixture.

The precipitation of calcium carbonate in the suspension provides for the capture of gaseous CO ₂ from a group of gas mixtures and long-term mineral sequestration from the captured CO ₂ atmosphere. The fine precipitate suspension and coarse precipitate slurry are further processed to separate the calcium carbonate precipitate from the solution.

CCS System with Precipitate Treatment In the CCS system with precipitate treatment , shown in FIG. 6, calcium oxide is fed from railcar 120 to calcium oxide reservoir 122 in solution preparation area 130 by a conveyor belt. The calcium oxide is conveyed to a calcium hydroxide mixing tank 124 where the calcium oxide is hydrated with water to produce calcium hydroxide (solid). Heat from the exothermic reaction is used to dry the precipitate in the final precipitate processing stage. The exhaust heat is released through the exhaust pipe 70.

  Calcium hydroxide is transported to the replenishment tank 126, where the calcium hydroxide solution is mixed, the pH and surfactant concentration 131 are adjusted to the optimum operating range, and the solution main reflux 160 is supplied to the replenishment tank. Return to 126 for reuse.

The calcium hydroxide solution flows from the refill tank 126 to the calcium hydroxide operation reservoir 128. The calcium hydroxide solution in the operational reservoir 128 has a replenished alkalinity and surfactant concentration and is piped to the heat exchanger 132 adjacent to the dehydration chamber 60. The solution is pumped by a calcium hydroxide solution pump through a solution supply longitudinal pipe from the heat exchanger 132 to a solution delivery manifold located at the top of the reaction chamber of the CO ₂ scrubber 5. The calcium hydroxide solution mixes with the gas mixture stream in the mesh panel assembly of the floss generator to create a calcium hydroxide bubble column in the reaction chamber.

The bubble column fills the reaction chamber and reacts with CO ₂ to produce a calcium carbonate precipitate. The calcium carbonate precipitate is transferred from the reaction chamber to the dehydration chamber 60 in suspension in the bubble wall. The gas released from the bubbles when the bubbles are dehydrated is released into the atmosphere via the exhaust pipe 70. The precipitate is swept into the underwater portion of the dehydration chamber 60 by the spraying of droplets from the spray nozzle. The hydrodynamic flow in the underwater portion of the dehydration chamber 60 and the underwater portion of the reaction chamber transfers the precipitate in suspension to the precipitation tank 90. In the sedimentation tank 90, the heavy sediment settles into the slurry channel at the bottom of the tank and the light sediment remains in the suspension.

  The sediment suspension having a small weight flows from the sediment tank 90 into the storage tank 141 in the fine sediment treatment area 140 through the solution flow main pipe 102. The fine sediment treatment in which the fine sediment suspension flows from the storage tank 141 to the floss flotation tank 145 operates in a continuous mode. Compressed air introduced into a plurality of nozzles (not shown) at the bottom of the tank fills the floss flotation tank 145 with bubbles. A portion of the sediment floating in the solution is transferred to the aqueous floss at the top of the flotation tank 145 by bubbles. The bubbles are directed to the receiving bat 147 by the shape at the top of the tank. A spray nozzle at the top of the receiving vat 147 dehydrates the air bubbles and the remaining fine precipitate slurry passes through the funnel portion of the receiving vat 147 to the Siemens model J-VAC, combined high diaphragm plate filter press / vacuum dryer 150 Lead. The solution is pressed from the slurry in a filter press 150 to form a filter cake. Hot water from the heat exchanger 125 around the calcium hydroxide mixing tank 124 heats the air to about 80 ° C. Hot air is drawn through the filter cake to dry the filter cake by partial vacuum. The filter cake is conveyed from the filter press 150 to the Siemens rotating cylindrical tumble dryer 153. Hot water from the heat exchanger 125 around the calcium hydroxide mixing tank 124 heats the air in the tumble dryer 153 to about 80 ° C. The filter cake is further dried and rotated to separate as individual granules. The dried fine precipitate is conveyed to a rail car 155 for sale or reuse.

  The calcium hydroxide solution main stream flows from the floss flotation tank 145 into the solution circulation main pipe 160. The solution flows into the replenishing tank 126 through the solution circulation main pipe 160. The flow of the solution pressed from the slurry to form a filter cake flows to the fine slurry solution circulation pipe, the solution circulation main pipe 160 and then flows into the replenishing tank 126. The alkalinity, surfactant concentration is adjusted to the optimum range, and the calcium hydroxide solution is recycled back to the system.

  The coarse sediment slurry is discharged from the slurry outlet 103 at the bottom of the precipitation tank 90 to the primary storage tank 172 in the coarse sediment treatment area 170 via the slurry pipe 171. The coarse precipitate treatment is operated in batch mode. The storage tank 172 is partially filled with the flow from the precipitation tank 90 over time, and then the amount of slurry inside is emptied and discharged to the coarse slurry precipitation tank 175. The coarse precipitate is precipitated from the slurry to become a concentrated slurry, and this concentrated slurry is pumped to a storage vat (177). The concentrated coarse precipitate slurry flows from the storage vat 177 to one of the two Siemens model J-VAC, combined hiber diaphragm plate filter press / vacuum dryer 150 via the branch funnel portion of the storage vat 177. The filter press operates simultaneously to provide two paths for dewatering and drying the coarse sediment slurry. The solution is pressed from the filter cake. Hot water from the heat exchanger 125 around the calcium hydroxide mixing tank 124 heats the air to about 80 ° C. Hot air is drawn through the filter cake to dry the filter cake. The filter cake is conveyed from the filter press 150 to one of the two Siemens rotating cylindrical tumble dryers 153. Hot water from the heat exchanger 125 around the calcium hydroxide mixing tank 124 heats the air in the tumble dryer 153 to about 80 ° C. The filter cake is further dried and spun and separated into individual granules. The dried coarse precipitate is conveyed to a rail car 155 for sale or reuse.

The calcium hydroxide solution from the coarse precipitate slurry flows into the secondary treatment pipe 181 from the slurry precipitation tank 175. The flow of the solution pressed from the slurry to form the filter cake flows through the slurry solution circulation pipe, the secondary processing pipe 181, and then flows into the secondary processing storage tank 183. The secondary slurry process 180 is operated in a batch mode. The storage tank 183 is filled with the flow of the solution from the slurry precipitation tank 175 over time, and then the volume of the solution is emptied and discharged to the secondary coarse slurry precipitation tank 185. The heavy sediment that settles from the solution while the secondary storage tank 183 is filled is forcibly sent to the primary coarse sediment slurry storage tank 172 via the slurry circulation pipe 184 by hydrostatic pressure. The volume of solution from the secondary storage tank 183 is largely transferred to the secondary precipitation tank 185 when the secondary storage tank 183 is partially filled. The coarse precipitate precipitated from the solution in the secondary precipitation tank 185 is forcibly sent to the primary coarse precipitate slurry storage tank 172 via the slurry circulation pipe 184 by hydrostatic pressure. When the volume of the solution fills most of the secondary storage tank 183, the solution is repeatedly transported from the secondary storage tank 183 to the secondary precipitation tank 185, and fine precipitates from the secondary precipitation tank 185 are obtained. Is transferred to the high pH tank 188 via the solution transfer pipe 187. The solution containing the fine precipitate in a suspended state in the high pH tank 188 is conveyed to the solution flow main pipe 135 at the starting point of the fine precipitate treatment area 140 via the secondary solution circulation pipe 190. The fine precipitate suspension from the high pH tank 188 is treated with the main stream of the fine precipitate suspension from the precipitation tank 90 of the CO ₂ scrubber 5. In the low pH tank 189, the alkalinity is adjusted to about pH 7.0 for the water returned to the environment.

Calcium carbonate precipitate is sold as an admixture for inorganic fillers, acidic soil neutralizers, slope stabilizers, fluidizers and Portland cement. In purified form, precipitated calcium carbonate (PCC) is used in the manufacture of paper, plastic, food and pharmaceutical products. The reuse or sale of useful calcium carbonate from recovered CO ₂ offsets at least a portion of the cost of CCS.

Alternative Embodiments A preferred form of the invention cools the gas in the bubbles as the bubbles move down in the reaction chamber, while a slightly preferred form of the invention performs without cooling the bubbles or solution. .

The CO ₂ scrubber of the present invention can optionally incorporate a sodium hydroxide solution for CCS. Sodium hydroxide is prepared by a chlor-alkali process by electrolysis of an aqueous sodium chloride solution. When using the CO ₂ scrubber with sodium hydroxide solution, the reaction product is a sodium bicarbonate. The sodium hydroxide solution can be used together with the calcium hydroxide solution or alone. To promote, catalyze or improve the reaction, potassium hydroxide can be added to the calcium hydroxide or sodium hydroxide solution.

The CO ₂ scrubber of the present invention can be used with an aqueous suspension of calcium carbonate for flue gas desulfurization (FGD). When forced feed air is injected into the underwater portion of the reaction chamber, the reaction product is calcium sulfate. When a CO ₂ scrubber is used in combination with the FGD, the FGD removes the sulfuric acid that interferes with the precipitation of calcium carbonate in the CO ₂ scrubber from the gas mixture, and between the calcium carbonate suspension in the FGD and the sulfuric acid. Gaseous CO ₂ released from the reaction is conveyed to the CO ₂ scrubber in a mixed gas stream. The calcium carbonate precipitate from the CCS process can be used to produce an aqueous suspension of calcium carbonate for FGD.

Conclusion, effect and scope
CONCLUSION The CO ₂ scrubber of the present invention includes the following functions and features and increases the removal efficiency of gaseous CO ₂ from mixed gas over the prior art.

The liquid-gas surface area of the calcium hydroxide solution between the gaseous CO ₂ in the mixed gas stream and the calcium hydroxide solution increases exponentially to increase the mass between the CO ₂ gas and the calcium hydroxide solution. Promote movement.

Combustion exhaust gas is bubbled to increase the contact time between gaseous CO ₂ in the mixed gas stream and the calcium hydroxide solution to promote mass transfer between the CO ₂ gas and the calcium hydroxide solution. Enclosed.

  At least some of the bubbles cause rupture and reformation, and the ruptured bubbles form a large number of microdroplets with various radii, each reshaped bubble being a separate volume of the mixed gas stream, a microdroplet of solution Enclose individual numbers and individual volumes of solution vapor.

The temperature of the calcium hydroxide solution is lowered to increase the solubility of gaseous CO _{2 in} the calcium hydroxide solution.

CO ₂ vapor pressure in bubbles, to increase the solubility of gaseous CO ₂ to calcium hydroxide solution, increases.

A gas mixture containing gaseous CO ₂ will cause a common bubble wall of the calcium hydroxide solution to move from a relatively small bubble with a high vapor pressure to a relatively large bubble with a low vapor pressure between two bubbles at different pressures. Spread through.

Calcium hydroxide is used in an alkaline solution to react with gaseous CO ₂ to recover calcium carbonate as a reaction product.

The recovered CO ₂ is reused as a useful calcium carbonate product that is sold to recover at least part of the cost of CCS.

Advantages The CO ₂ scrubber of the present invention can directly remove CO ₂ from the atmosphere, post-combustion exhaust gas, and processes that release CO ₂ as a result of processing or manufacturing.

The CO ₂ scrubber of the present invention can incorporate other alkaline earth metal hydroxide solutions or mixtures of alkaline earth metal hydroxide solutions for CCS.

The CO ₂ scrubber of the present invention can incorporate an aqueous suspension of calcium carbonate for flue gas desulfurization (FGD). When forced feed air is injected into the underwater portion of the reaction chamber, the reaction product is calcium sulfate (gypsum). FGD gypsum is used in the manufacture of cement and gypsum panels.

The CO ₂ scrubber of the present invention can be integrated with FGD to remove SO _X and CO ₂ from a mixed gas stream. An aqueous suspension of calcium carbonate can be produced from the calcium carbonate precipitate that is the reaction product in the CO ₂ scrubber, and the CO ₂ gas released during the reaction between the calcium carbonate precipitate and sulfuric acid in the FGD. Is conveyed to a CO ₂ scrubber in the form of a mixed gas.

Scope The exemplary processes and apparatus described above are presented for purposes of illustration and explanation, and are not intended to be exhaustive or to limit the scope of the invention to the same forms described. Modifications and variations are possible in light of the above teachings. The embodiments best describe the invention and its practical application so that others skilled in the art can best understand the invention in various embodiments and with various modifications suitable for the particular use intended. It was chosen to allow use.

  The scope of the present invention is defined by the following claims.

Claims (14)

A method for capturing and sequestering gaseous carbon dioxide (CO ₂ ) from a mixed gas stream, wherein a reaction chamber is used, and the mesh panel assembly in the reaction chamber has a plurality of mesh openings. In
Continuously saturating the mesh panel assembly having a plurality of mesh panels with a solution containing calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ );
Passing the gas stream having gaseous CO ₂ through the saturated mesh panel assembly to form an aqueous floss, wherein the froth bubbles have an internal volume filled with the mixed gas;
At least some of the bubbles are ruptured and reformed, the ruptured bubbles forming a large number of microdroplets with various radii, each reshaped bubble being a separate volume of the gas stream, a micro of the solution Enclosing an individual number of droplets and an individual volume of solution vapor;
The size of the bubbles formed in the aqueous floss is limited by limiting the size of the openings in the mesh panel, thereby forming innumerable uniform small bubbles, and the CO ₂ molecules and the microscopic bubbles. Maximizing contact between the droplets and the inner and outer surfaces of the myriad small bubbles;
Cooling the solution before the solution passes through the saturated mesh panel, and cooling the gas in the bubbles as the bubbles move down through the reaction chamber;
The aqueous floss and the gas stream are moved together downward through the reaction chamber to increase the reaction time between the gas stream and the myriad bubbles and to increase the pressure of the aqueous floss Reducing the bubble size and increasing the solubility of CO ₂ molecules in the solution;
Minimizing the mean free path of the CO ₂ molecules in the bubbles by reducing the volume of the bubbles to reduce the distance between the inner surface of each bubble and the microdroplets in each bubble, thereby Maximizing contact between the CO ₂ molecules and the solution used to form the bubbles and the microdroplets;
The CO ₂ molecules brought into the solution are converted into calcium carbonate (CaCO ₃ ) molecules by the reaction of the CO ₂ molecules with the calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ ) in the solution. Capturing by producing and precipitating the calcium carbonate from the solution.   The method of claim 1, further comprising cooling the solution before the solution passes through the saturated mesh panel. 2. The method of claim 1, wherein the reaction chamber is an elongated, vertical chamber having a bottom in fluid communication with a horizontal dehydration chamber, and an adjustable outlet panel is provided between the reaction chamber and the dehydration chamber. The size of the openings can be changed between, and the method further comprises:
Changing the size of the opening to be adjustable between the lower part of the reaction chamber and the dehydration chamber.   4. The method of claim 3, further comprising the step of dehydrating the aqueous floss in the dehydration chamber and releasing the dehydrated gas stream into the atmosphere. The method of claim 1, further comprising disposing a precipitation tank below the reaction chamber, the method further comprising:
Allowing the precipitated calcium carbonate to settle downward by gravity into the precipitation tank.   6. The method of claim 5, further comprising the step of continuously removing the precipitated calcium carbonate from the precipitation tank.   The method of claim 1, further comprising separating the sulfur from the gas stream by reacting sulfur with calcium carbonate in suspension. A method for capturing and sequestering gaseous carbon dioxide (CO ₂ ) from a mixed gas stream, wherein a reaction chamber is used and the mesh panel assembly in the reaction chamber has a plurality of mesh openings.
Continuously saturating the mesh panel assembly having a plurality of mesh panels with a solution containing calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ );
Passing the gas stream having gaseous CO ₂ through the saturated mesh panel assembly to form an aqueous floss, wherein the froth bubbles have an internal volume filled with the mixed gas;
At least some of the bubbles are ruptured and reformed, the ruptured bubbles forming a large number of microdroplets with various radii, each reshaped bubble being a separate volume of the gas stream, a micro of the solution Enclosing an individual number of droplets and an individual volume of solution vapor;
The size of the bubbles formed in the aqueous floss is limited by limiting the size of the openings in the mesh panel, thereby forming innumerable uniform small bubbles, and the CO ₂ molecules and the microscopic bubbles. Maximizing contact between the droplets and the inner and outer surfaces of the myriad small bubbles;
The aqueous floss and the gas stream are moved together downward through the reaction chamber to increase the reaction time between the gas stream and the myriad bubbles and to increase the pressure of the aqueous floss Reducing the bubble size and increasing the solubility of CO ₂ molecules in the solution;
Minimizing the mean free path of the CO ₂ molecules in the bubbles by reducing the volume of the bubbles to reduce the distance between the inner surface of each bubble and the microdroplets in each bubble, thereby Maximizing contact between the CO ₂ molecules and the solution used to form the bubbles and the microdroplets;
The CO ₂ molecules brought into the solution are converted into calcium carbonate (CaCO ₃ ) molecules by the reaction of the CO ₂ molecules with the calcium ions (Ca ²⁺ ) and hydroxide ions (OH ⁻ ) in the solution. Capturing by producing and precipitating the calcium carbonate from the solution.   9. The method of claim 8, further comprising cooling the gas inside the bubble as the bubble moves down through the reaction chamber.   9. The method of claim 8, wherein the solution is cooled before passing the solution through the mesh panel.   9. The method of claim 8, wherein the solution contains calcium hydroxide and potassium hydroxide. A method for capturing and sequestering gaseous carbon dioxide (CO ₂ ) from a mixed gas stream, wherein a reaction chamber is used and the mesh panel assembly in the reaction chamber has a plurality of mesh openings. ,
Continuously saturating the mesh panel assembly having a plurality of mesh panels with a sodium hydroxide solution;
Passing the gas stream having gaseous CO ₂ through the saturated mesh panel assembly to form an aqueous floss, wherein the froth bubbles have an internal volume filled with the mixed gas; ,
At least some of the bubbles are ruptured and reformed, the ruptured bubbles forming a large number of microdroplets with various radii, each reshaped bubble being a separate volume of the gas stream, a micro of the solution Enclosing an individual number of droplets and an individual volume of solution vapor; and
The size of the bubbles formed in the aqueous floss is limited by limiting the size of the openings in the mesh panel, thereby forming innumerable uniform small bubbles, and the CO ₂ molecules and the microscopic bubbles. Maximizing contact between the droplets and the inner and outer surfaces of the myriad small bubbles;
The aqueous floss and the gas stream are moved together downward through the reaction chamber to increase the reaction time between the gas stream and the myriad bubbles and to increase the pressure of the aqueous floss Reducing the bubble size and increasing the solubility of CO ₂ molecules in the solution;
Minimizing the mean free path of the CO ₂ molecules in the bubbles by reducing the volume of the bubbles to reduce the distance between the inner surface of each bubble and the microdroplets in each bubble, thereby Maximizing contact between the CO ₂ molecules and the solution used to form the bubbles and the microdroplets;
Capturing CO ₂ molecules brought into the solution by forming sodium bicarbonate molecules by reaction of the CO ₂ molecules with the sodium hydroxide solution; and the sodium bicarbonate from the solution; And precipitating.   13. The method of claim 12, further comprising cooling the mixed gas in the myriad of bubbles as the bubbles move down through the reaction chamber. A device that captures and sequesters gaseous carbon dioxide CO ₂ from a mixed gas stream, where calcium ions or sodium ions and hydroxide ions react with carbon dioxide to produce calcium carbonate or sodium bicarbonate as a precipitate. In the apparatus configured as follows:
A reaction chamber having an upper portion and a lower portion and extending longitudinally;
A mesh panel array comprising a series of mesh panels disposed in the upper portion of the reaction chamber;
Means for continuously saturating the mesh panel with a solution containing calcium ions or sodium ions and hydroxide ions;
Floss generator means disposed above the mesh panel array;
A duct for conveying the mixed gas stream to the floss generator means;
With
Forming an aqueous froth having innumerable small bubbles by the floss generator means, and filling the internal volume of the bubbles with gas from the mixed gas stream containing gaseous carbon dioxide;
Means for cooling the calcium hydroxide or sodium hydroxide solution;
Means for pressurizing the aqueous floss to reduce the size of the myriad bubbles as the floss moves to the lower portion of the reaction chamber;
A precipitation tank means disposed below the reaction chamber for collecting a precipitate of calcium carbonate or sodium bicarbonate;
An apparatus comprising:

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