Systems and methods of capturing carbon dioxide and minimizing production of carbon dioxide

Abstract

A method of capturing carbon dioxide emitted by a power plant includes providing a reactor vessel having a shell with a top and a bottom, introducing an exhaust gas stream into the reactor vessel, the exhaust gas stream containing carbon dioxide, whereby the exhaust gas stream rises toward the top of the reactor vessel. The method includes introducing an organic sorbent solution into the reactor vessel near the top of the reactor vessel so that the organic sorbent solution falls toward the bottom of the reactor vessel, mixing the rising exhaust gas stream with the falling organic sorbent solution to precipitate calcium carbonate, and removing the calcium carbonate from the bottom of the reactor vessel, whereby the calcium carbonate includes the carbon dioxide from the exhaust gas stream.

Claims

1. A method of capturing carbon dioxide emitted by a power plant comprising: providing a reactor vessel having a shell with a top and a bottom; introducing an exhaust gas stream into said reactor vessel via an exhaust gas inlet, said exhaust gas stream containing carbon dioxide, wherein said exhaust gas stream rises toward the top of said reactor vessel; introducing an organic sorbent solution into said reactor vessel at a location of said reactor vessel that is above said exhaust gas stream inlet so that said organic sorbent solution falls toward the bottom of said reactor vessel; mixing said rising exhaust gas stream with said falling organic sorbent solution to precipitate calcium carbonate; providing at least one tray assembly inside said reactor vessel, said at least one tray assembly comprising a pivoting tray; collecting said calcium carbonate on said pivoting tray; and removing said calcium carbonate from the bottom of said reactor vessel, wherein said calcium carbonate includes said carbon dioxide from said exhaust gas stream.

2. The method as claimed in claim 1, wherein said organic sorbent solution comprises raw sugar beet juice and lime milk.

3. The method as claimed in claim 2, wherein the mixing step includes deriving a sugar rich solution from said raw sugar beet juice.

4. The method as claimed in claim 3, further comprising separating said sugar rich solution from said calcium carbonate and removing said sugar rich solution from said reactor vessel.

5. The method as claimed in claim 4, further comprising removing moisture from said sugar rich solution to generate crystallized sugar.

6. The method as claimed in claim 1, further comprising after the mixing step, removing said exhaust gas stream from the top of said reactor vessel, wherein said exhaust gas stream removed from the top of said reactor vessel has less carbon dioxide than said exhaust gas stream introduced into said reactor vessel.

7. The method as claimed in claim 1, wherein the introducing said exhaust gas stream into said reactor vessel comprises: burning a fuel at a power plant to generate energy and said exhaust gas stream; using a conduit to connect said reactor vessel with said power plant; and directing said exhaust gas stream through said conduit and into said reactor vessel.

8. The method as claimed in claim 7, wherein said power plant is a coal fired power plant or a natural gas power plant.

9. The method as claimed in claim 1, wherein said pivoting tray comprises a tray bottom having a plurality of holes formed in said tray bottom, the method further comprising passing said organic sorbent solution through said plurality of holes in said tray bottom as said calcium carbonate is collected on said tray bottom.

10. The method as claimed in claim 9, wherein said at least one tray assembly further comprises a counterweight coupled with said pivoting tray, and a pivot that enables said pivoting tray to pivot from an upright position to a down position when the combined weight of said pivoting tray and said calcium carbonate collected on said pivoting tray is greater than the weight of said counterweight.

11. The method as claimed in claim 10, further comprising pivoting said pivoting tray from the upright position to the down position when the combined weight of said pivoting tray and said calcium carbonate collected on said pivoting tray is greater than the weight of said counterweight for dumping said calcium carbonate collected on said pivoting tray toward the bottom of said reactor vessel, and, after the dumping step, returning said pivoting tray to the upright position under the weight of said counterweight.

12. The method as claimed in claim 9, wherein said tray bottom has an inner edge that is serrated to separate said organic sorbent solution flowing over said serrated inner edge into sheet-like films that flow down toward the bottom of said reactor vessel.

13. The method as claimed in claim 1, wherein the step of providing at least one tray assembly inside said reactor vessel comprises providing a plurality of tray assemblies inside said reactor chamber, wherein said tray assemblies are spaced from one another between the top and the bottom of said shell of said reactor vessel.

14. A method of making sugar using carbon dioxide gas emitted by a power plant comprising: processing sugar beets to generate raw sugar beet juice; mixing said raw sugar beet juice with lime milk to product a sorbent solution; providing a reactor vessel having a shell with a top and a bottom; introducing an exhaust gas stream from a power plant into said reactor vessel via an exhaust gas inlet, said exhaust gas stream containing carbon dioxide, wherein said exhaust gas stream rises toward the top of said reactor vessel; introducing said sorbent solution containing said raw sugar beet juice and said lime milk into said reactor vessel at a location of said reactor vessel that is above said exhaust gas stream inlet so that said sorbent solution falls toward the bottom of said reactor vessel; mixing said rising exhaust gas stream with said falling sorbent solution to precipitate calcium carbonate that contains said carbon dioxide from said exhaust gas stream and a sugar rich solution derived from said raw sugar beet juice; providing one or more tray assemblies inside said reactor vessel, each said tray assembly comprising a pivoting tray; collecting said calcium carbonate on said pivoting trays; separating said sugar rich solution from said calcium carbonate; and removing said calcium carbonate from the bottom of said reactor vessel.

15. The method as claimed in claim 14, further comprising removing moisture from said sugar rich solution to generate crystallized sugar.

16. The method as claimed in claim 14, further comprising after the mixing step, removing said exhaust gas stream from the top of said reactor vessel, wherein said exhaust gas stream removed from the top of said reactor vessel has less carbon dioxide than said exhaust gas stream introduced into said reactor vessel.

17. The method as claimed in claim 14, wherein the introducing said exhaust gas stream into said reactor vessel comprises: burning a fuel at a power plant to generate energy and said exhaust gas stream; using a conduit to connect said reactor vessel with said power plant; and directing said exhaust gas stream generated at said power plant through said conduit and into said reactor vessel.

18. The method as claimed in claim 17, wherein said power plant is a coal fired power plant or a natural gas power plant.

19. The method as claimed in claim 14, wherein said pivoting tray comprises a tray bottom having a plurality of holes formed in said tray bottom, the method further comprising allowing said organic sorbent solution to pass through said plurality of holes in said tray bottom as said calcium carbonate is collected on said tray bottom.

20. The method as claimed in claim 19, wherein said at least one tray assembly further comprises a counterweight coupled with said pivoting tray, and a pivot that enables said pivoting tray to pivot from an upright position to a down position when the combined weight of said pivoting tray and said calcium carbonate collected on said pivoting tray is greater than the weight of said counterweight.

21. The method as claimed in claim 20, further comprising pivoting said pivoting tray from the upright position to the down position when the combined weight of said pivoting tray and said calcium carbonate collected on said pivoting tray is greater than the weight of said counterweight for dumping said calcium carbonate collected on said pivoting tray toward the bottom of said reactor vessel, and, after the dumping step, returning said pivoting tray to the upright position under the weight of said counterweight.

22. The method as claimed in claim 21, wherein said tray bottom has an inner edge that is serrated to separate said organic sorbent solution flowing over said serrated inner edge into sheet-like films that flow down toward the bottom of said reactor vessel.

23. The method as claimed in claim 14, wherein the step of providing one or more tray assemblies inside said reactor vessel comprises providing a plurality of tray assemblies inside said reactor chamber, wherein said tray assemblies are spaced from one another between the top and the bottom of said shell of said reactor vessel.

Description

BRIEF DESCRIPTION OF THE DRAWING

(1) FIG. 1A shows a perspective view of an exhaust gas treatment system including a carbon capture unit having a shell, a top, a bottom, a tray assembly having a tray, and a calcium carbonate sieve, in accordance with one embodiment of the present invention.

(2) FIG. 1B shows a perspective view of the carbon capture unit shown in FIG. 1A.

(3) FIGS. 2A-2C show the shell of the carbon capture unit shown in FIG. 1A.

(4) FIGS. 3A-3C show the top of the carbon capture unit shown in FIG. 1A.

(5) FIGS. 4A-4B show the bottom of the carbon capture unit shown in FIG. 1A.

(6) FIGS. 5A-5D show the tray assembly of the carbon capture unit shown in FIG. 1A.

(7) FIGS. 6A-6D show the tray of the tray assembly shown in FIGS. 5A-5D.

(8) FIGS. 7A-7D show the calcium carbonate sieve of the carbon capture unit shown in FIG. 1A.

(9) FIG. 8 shows a cross-sectional view of a carbon capture unit, in accordance with one embodiment of the present invention.

(10) FIGS. 9A and 9B show a tray for a tray assembly of a carbon capture unit, in accordance with one embodiment of the present invention.

DETAILED DESCRIPTION

(11) Referring to FIGS. 1A and 1B, in one embodiment, an exhaust gas treatment system 20 is preferably adapted to receive and treat exhaust gases from a power plant such as a coal burning power plant that produces electricity. In one embodiment, the exhaust gas treatment system 20 preferably includes a particulate recovery system 22 that removes particulate material (e.g., ash) from an exhaust gas, a sulfur gas recovery unit 24 that removes sulfur from the exhaust gas stream, a heat recovery unit 26 that removes heat energy from the exhaust gas stream, and a carbon capture unit 28 that remove carbon dioxide from the exhaust gas stream.

(12) In one embodiment, the carbon capture unit 28 preferably includes a shell 30, a top 32, a sparger 34 located inside the top, a bottom 36, one or more tray assemblies 38, and one or more calcium carbonate sieves 40 located near a lower end of the shell 30. As will be described in more detail herein, the carbon capture unit 28 uses sugar beet juice and lime milk to remove carbon dioxide from the exhaust gas stream of a power plant such as a coal fired power plant.

(13) Referring to FIGS. 1B and 2A-2C, in one embodiment the shell 30 has a cylindrical-shaped side wall 42 having an upper end 44 and a lower end 46. The shell 30 is preferably made of stainless steel. In one embodiment, the side wall 42 has as outer diameter OD.sub.1 of about 4,000 cm (FIG. 2C). The shell desirably includes an exhaust gas stream inlet 48 located adjacent the lower end 46 of the side wall 42, a reacted gas outlet 50 located adjacent the upper end 44 of the side wall 42, and a raw juice inlet 52 located above the exhaust gas stream inlet 48 and below the reacted gas outlet 50.

(14) The side wall 42 of the shell 30 surrounds a reaction chamber 54 in which a reaction takes place among an exhaust gas stream containing carbon dioxide, lime milk, and raw sugar beet juice to, inter alia, capture carbon dioxide present in the exhaust gas stream. The exhaust gas stream containing the carbon dioxide rises inside the reaction chamber and the raw sugar beet juice is introduced at the top and moves down within the reaction chamber. After the reaction takes place, reacted gas minus the carbon dioxide that has been removed is discharged from the shell 30 via the reacted gas outlet. The reaction creates calcium carbonate sludge that contains the extracted carbon dioxide. The calcium carbonate sludge is removed from the carbon capture unit 28 via the bottom 36 of the unit.

(15) Referring to FIGS. 3A-3C, in one embodiment, the carbon capture unit preferably includes a top 32 (FIG. 1A) that covers the upper end of the shell 30 (FIG. 2A). The top 32 preferably has an outer diameter OD.sub.2 of about 4,000 cm that matches the OD.sub.1 of the shell 30 (FIG. 2C). Referring to FIG. 3C, in one embodiment, the top 32 contains the sparger 34 that introduces the raw beet juice at the top of the reaction chamber.

(16) Referring to FIGS. 4A-4B, in one embodiment, the carbon capture unit preferably includes a bottom 36 (FIG. 1A) that covers the lower end of the shell 30 (FIG. 2A). In one embodiment, the bottom 36 has spaced legs 56 that support the bottom on a surface such as a floor. The bottom has a calcium carbonate sludge outlet 58 for removing calcium carbonate sludge from the reaction chamber through the bottom 36 of the carbon capture unit. Referring to FIG. 4B, in one embodiment, the bottom 36 has an outer diameter OD.sub.3 of about 4,000 cm that matches the outer diameter OD.sub.1 of the shell 30 (FIG. 2C) and the outer diameter OD.sub.2 of the top 32.

(17) Referring to FIGS. 5A-5D, in one embodiment, the carbon capture unit includes one or more tray assemblies 38 disposed inside the reaction chamber. In one embodiment, a tray assembly 38 preferably includes a mounting plate 60, a tray support frame 62 that extends inwardly from the mounting plate 60, a tray 64 coupled with a counterweight plate 66, and a pivot 68 that enables the tray to drop down when filled with a sufficient amount of calcium carbonate sludge to overcome the weight of the counterweight plate 66.

(18) In one embodiment, the tray support frame 62 desirably includes a pair of horizontally extending support legs 70A, 70B and a pair of diagonally extending support legs 72A, 72B that connect together at the pivot 68. When the tray 64 is in the upright position shown in FIGS. 5A-5D, the horizontally extending support legs 70A, 70B function as a hard stop for the counterweight plate 66 to limit upward pivoting movement of the tray 64.

(19) In one embodiment, during a reaction process, calcium carbonate sludge is collected on the tray 64. When the weight of the calcium carbonate sludge is greater than the weight of the counterweight plate 66, the tray 64, under the weight of the calcium carbonate sludge that it holds, will pivot down toward the bottom of the shell 30 (FIG. 1B). When the plate 64 pivots down, the plate will dump the calcium carbonate sludge that has been collected on the plate. Once the sludge has been dumped, the counterweight plate 66 will pivot the plate back to the upright position shown in FIGS. 5A-5D.

(20) Referring to FIGS. 6A-6D, in one embodiment, the tray 64 preferably includes a tray bottom 74 having a plurality of holes 76 passing through the tray bottom. The plurality of holes 76 allow the raw juice to pass through the holes while the tray bottom 74 collects the calcium carbonate sludge. The tray 64 desirably has a rear wall 78, a front wall 80, a first side wall 82, and a second side wall 84. In one embodiment, the walls 78, 80, 82, 84 project upwardly from the tray bottom 74. The walls may be vertical walls. In one embodiment, the front wall 80 may be shorter than the rear wall 78 and the side walls 82, 84.

(21) Referring to FIG. 6B, in one embodiment, the tray 64 has a length L.sub.1 of about 750 cm, and a width W.sub.1 of about 750 cm. In one embodiment, the plurality of holes 76 are evenly spaced from one another and cover most of the area of the tray bottom 74.

(22) Referring to FIG. 6C, in one embodiment, the front wall 80 has a height H.sub.1 of about 96 cm and the rear wall 74 and the side walls 82, 84 have a height H.sub.2 of about 156 cm. Thus, in one embodiment, the front wall is 60 cm shorter than the rear and side walls.

(23) Referring to FIGS. 7A-7D, in one embodiment, the carbon capture unit 28 (FIG. 1B) preferably includes a calcium carbonate sieve 40 that directs the dumped calcium carbonate sludge toward the calcium carbonate discharge port 58 (FIG. 4A) located in the bottom of the unit. In one embodiment, the sieve 40 desirably includes a rear wall 86, a sloping bottom 88, and a pair of opposing side walls 90, 92 that project upwardly from the sloping bottom wall and inwardly from the rear wall 86.

(24) In one embodiment, the rear wall 86 is mounted to an inner surface of the shell 30 (FIG. 2C) with the sloping bottom 88 sloping away from the shell and toward the lower end of the shell. The sieve 40 is preferably adapted to direct the falling calcium carbonate sludge toward the center and bottom of the reaction chamber so that the sludge may be removed from the bottom of the carbon capture unit.

(25) Referring to FIG. 7C, in one embodiment, the calcium carbonate sieve 40 has a length L.sub.2 of about 4,400-4,500 cm and a width W.sub.2 of about 3,200 cm.

(26) Referring to FIG. 7D, in one embodiment, the distance between the free end of the sloping bottom 88 and the upper edge of the side wall 90 defines a height H3 of about 5,000-5,100 cm. In one embodiment, the sloping bottom 88 and the upper edge of the side wall 90 define an angle α.sub.1 of about 45 degrees.

(27) Referring to FIG. 8, in one embodiment, a carbon capture unit 128 has as its core unit a single reactor vessel 130, vertical in orientation, cylindrical in shape, with hemispherical dish ends 132, 136. An organic absorbent solution, such as raw beet juice, is brought from a storage container to the reactor 130 by gravitational feed. Inside the reactor 130 a sparger 134 is placed with suitably sized and configured nozzles that spray the organic fluid into the inner volume of the vessel 130.

(28) Collection tray assemblies 138 with trays 164 having serrated edges are disposed within the reactor vessel 130. The descending fluid from the sparger 134 collects in the trays 164, and when this overflowing fluid passes over the serrated edges, they separate the overflowing fluid into sheet-like films. The bottom of the trays 164 have multiple small apertures which allow the fluid collected in each tray to again pour out of the tray from under the surface in the form of thin streams. When the weight of the precipitated calcium carbonate exceeds the weight of the counterweight plate coupled with the tray, the tray swivels and dumps the calcium carbonate toward the lower end of the reactor vessel 130. At the bottom, calcium carbonate sieves 140 receive the dumped calcium carbonate and via an outlet 158 discharges it into receiving equipment, which may be a conveyer belt or receiving bin.

(29) Above the calcium carbonate sieves 140, one or more inlet nozzles 148 are arranged around the body of the shell 130. These inlet nozzles 140 connect to the pipe which will bring the exhaust gas stream containing the CO.sub.2 from the boiler or any other source into the reactor. These nozzles 140 project inwardly to create an upward flow of the flue gas to create turbulent mixing with the descending fluid streams.

(30) In one embodiment, one or more vents 194 are provided at the top of the unit 128 to allow for the escape of the remaining vented gases. The vented gases do not include carbon dioxide, which has been captured in the calcium carbonate sludge.

(31) In one embodiment, at the bottom of the reactor chamber 130, a drain 196 is provided so that unreacted absorbent fluid can be collected and re-circulated back into the reactor vessel. Orifices 198, 200 for viewing, temperature measurement, gas flow measurement, pressure measurement, sampling tubes, etc. may be provided on the reactor vessel 130.

(32) Referring to FIG. 9A, in one embodiment, the carbon capture unit preferably includes a pivoting or swiveling tray 164 having a tray bottom 174 with a plurality of small, spaced apertures 176. Referring to FIG. 9B, in one embodiment, the tray 164 has a serrated edge 202 at the inner edge of the tray bottom 174. In one embodiment, the overflowing fluid collected on the tray passes over the serrated edge 202, whereby the serrated edge separates the overflowing fluid into sheet-like films that flows down toward the bottom of the reaction chamber.

(33) Although the present invention is not limited by any particular theory of operation, it is believed that using the CO.sub.2 from power plants to clarify beet juice will result in an immense net reduction of CO.sub.2 emissions as the CO.sub.2 would not come from the combustion of fossil fuel as is being done in conventional sugar refineries. Rather, CO.sub.2 would not have to be generated by sugar refineries for use in sugar refining processes, but may come from power plants by using the power plant flue gas as a source. Hence, the present invention provides a double savings of CO.sub.2 emissions because the power plant's CO.sub.2 emissions are used in the sugar refining process and the sugar refineries do not have to product CO.sub.2.

(34) Sugar refineries typically consume the same quantity of carbon dioxide as is emitted by a 100 MW coal fire power plant. Instead of the refineries producing CO.sub.2 to do the carbonation, that is adding CO.sub.2 which is expensive and created by a non-green process that uses fossil fuel in lime kilns, the CO.sub.2 used for carbonating the raw juice is provided by the CO.sub.2 emissions from a coal fired or natural gas power plant.

(35) The present invention provides a number of benefits including: 1) the CCU combines the best of two individual approaches in scrubber technology, that of using calcium oxide (lime) as sorbent along with an organic renewable amine as liquid, and both these sorbents enhance each other; 2) the CCU has lower capital cost and complexity compared to existing scrubber technology because it creates useable byproducts; 3) the CCU byproducts of calcium carbonate, molasses, sugar, and ethanol have a market value, 4) Molasses has value for power plants as a supplemental fuel which is equal to tons of coal which saves money and reduces emissions; and 5) the raw material lime stone is usually already being procured by power plants for their SO2 scrubbers.

(36) While the foregoing is directed to embodiments of the present invention, other and further embodiments of the invention may be devised without departing from the basic scope thereof, which is only limited by the scope of the claims that follow. For example, the present invention contemplates that any of the features shown in any of the embodiments described herein, or incorporated by reference herein, may be incorporated with any of the features shown in any of the other embodiments described herein, or incorporated by reference herein, and still fall within the scope of the present invention.