Self-Cleaning Desublimating Heat Exchanger for Gas/Vapor Separation

Abstract

A heat exchanger for separating a vapor component from a carrier gas is disclosed. The carrier gas is cooled in an outer chamber, causing a vapor component of the carrier gas to desublimate or condense onto an outer surface of an inner chamber, forming a solid product. A coolant is passed through the inner chamber to cool the carrier gas of the outer chamber. A means for causing the inner chamber to flex is provided, causing the solid product to fall from the outer surface of the inner chamber for collection. In this manner, the vapor component is separated from the carrier gas.

Description

This invention was made with government support under DE-FE0028697 awarded by. The Department of Energy. The government has certain rights in the invention.

FIELD OF THE INVENTION

This invention relates generally to the field of gas/vapor separation. More particularly, we are interested in the use of desublimating heat exchange as a method for extracting a vapor, like carbon dioxide, as a solid from a carrier gas, such as combustion flue gas.

BACKGROUND

The art of cryogenic capture of acid gases and other foulants from various carrier gas streams is a developing, but still young branch of gas/vapor separation. Gas/vapor separations are complicated in cryogenics by the tendency of these acid gases, such as carbon dioxide, to desublimate directly to a solid upon cooling at ambient pressures, rather than forming a liquid. The desublimated solids tend to foul heat exchangers, resulting in complex unit operations requiring unit operations such as solid/liquid separations, vapor/liquid separations, and extensive supporting unit operations.

The ability to directly separate acid gas vapors from their carrier gases without complex unit operations would be of great benefit to cryogenic gas processing.

United States patent publication numbers 4505728 and 4810274, both to Cheng, et al., teaches a vacuum freezing ambient pressure melting process and sub-triple point vapor processing unit for use therein. The process involves flash vaporization and crystallization, followed by a two-stage liquefaction by desublimation of the vapor, then melting the desublimate and crystals. The present disclosure differs from this disclosure in that the desublimate is formed but then melted for recovery. This disclosure is pertinent and may benefit from the devices disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.

United States patent publication number 4181508 to Schmidt, et al., teaches a method and apparatus for separating desublimatable components from gas mixtures. The process involves passing a gas with a desublimatable component through a heat exchanger with a traveling temperature profile, resulting in desublimation occurring along a traveling front in the exchanger, producing an inert gas free of the desublimatable component. Finally, the desublimate is recovered by melting the desublimate in the exchanger. The present disclosure differs from this disclosure in that the desublimate is formed but then melted for recovery. This disclosure is pertinent and may benefit from the devices disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.

German patent publication number 4134293 to Herzog, et al., teaches a process for recovering solvents from waste gases by condensing, freezing, or desublimating onto cold packing material. The recovery continues until the packing material is saturated, at which point the waste gas is transitioned to different cold packing material, while the recovered solvents are removed by warming the packing material to sublimate or melt the solid solvents. The present disclosure differs from this disclosure in that the solvent is recovered by sublimation or melting. This disclosure is pertinent and may benefit from the devices disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.

European patent publication number 0090004 by Hoffman teaches a liquid purification system comprising providing a liquid with impurities to a chamber for evaporation, condensation, and desublimation of the different components at different locations, with eventual melting to produce purified liquids. The present disclosure differs from this disclosure in that a liquid is purified rather than a gas, the desublimated impurities are recovered by melting, and evaporation is required. This disclosure is pertinent and may benefit from the devices disclosed herein and is hereby incorporated for reference in its entirety for all that it teaches.

SUMMARY

A heat exchanger for separating a vapor component from a carrier gas is disclosed. The carrier gas is cooled in an outer chamber, causing a vapor component of the carrier gas to desublimate or condense onto an outer surface of an inner chamber, forming a solid product. A coolant is passed through the inner chamber to cool the carrier gas of the outer chamber. A means for causing the inner chamber to flex is provided, causing the solid product to fall from the outer surface of the inner chamber for collection. In this manner, the vapor component is separated from the carrier gas.

The means for causing the inner chamber to flex may comprise a vibration inducing device attached to a portion of the heat exchanger, varying coolant pressure, or combinations thereof. The vibration inducing device may comprise a piezoelectric actuator, ultrasound emitter, voice coil, linear resonant actuator, shaker, exciter, hydraulic actuator, solenoid actuator, blunt object, manual shaking, or a combination thereof. The coolant pressure may be varied and the inner chamber constructed from expanding and contracting corrugated tubes, causing variations in the coolant pressure, resulting in expansion and contraction of the corrugated tubes. The coolant pressure may be varied rapidly by a pump operating at variable speeds, a valve rapidly opening and closing, or a combination thereof, causing the inner chamber to experience a hammering.

The vapor component may comprise water, carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, any hydrocarbon that has a higher freezing point than the temperature of the coolant, mercury, or combinations thereof. The carrier gas may comprise combustion flue gas, syngas, producer gas, natural gas, steam reforming gas, any hydrocarbon that has a lower freezing point than the temperature of the coolant, light gases, refinery off-gases, or combinations thereof.

The outer surface of the inner chamber may comprise a material that inhibits adsorption of gases, prevents deposition of solids, or a combination thereof. The material may comprise ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, natural diamond, man-made diamond, chemical-vapor deposition diamond, polycrystalline diamond, or combinations thereof.

The solid product may be collected by a device comprising an auger, a conveyor belt, a roller, a bin, a bag, a chute, or a combination thereof. The auger may be attached to the outer chamber by a hopper. The auger may pass the solids product through an outlet that comprises a restriction that provides a back pressure, pressurizing the solids, the outlet feeding a melter, the melter producing a liquid product.

The carrier gas may be provided to the outer chamber through an outlet for removal of the solids product.

The inner chamber may comprise a tube bundle. The outer chamber may comprise baffles that direct the carrier gas across the tube bundle. The heat exchanger may comprise a shell and tube, brazed plate, aluminum plate, plate, plate and frame, plate and shell, spiral, or plate fin style heat exchanger.

The coolant may comprise liquid nitrogen, ethane, methane, propane, refrigerants, and combinations thereof.

The inner chamber may comprise a flexible hose that is fed the coolant at a velocity that induces a resonance in the flexible hose, causing the flexible hose to undulate in a sinusoidal manner. The flexible hose may be situated to strike other flexible hoses or the outer chamber while undulating. The inner chamber may comprise a temperature sensor.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the advantages of the invention will be readily understood, a more particular description of the invention briefly described above will be rendered by reference to specific embodiments illustrated in the appended drawings. Understanding that these drawings depict only typical embodiments of the invention and are not therefore to be considered limiting of its scope, the invention will be described and explained with additional specificity and detail through use of the accompanying drawings, in which:

FIG. 1 shows an inner chamber of a heat exchanger for separating a vapor component from a carrier gas.

FIG. 2 shows an inner chamber of a heat exchanger for separating a vapor component from a carrier gas.

FIG. 3 shows an isometric cutaway view of a heat exchanger for separating a vapor component from a carrier gas.

FIG. 4 shows an isometric cutaway view of a heat exchanger for separating a vapor component from a carrier gas.

FIG. 5 shows a cutaway view of a heat exchanger for separating a vapor component from a carrier gas.

FIG. 6 shows an isometric cutaway view of an inner chamber of a heat exchanger for separating a vapor component from a carrier gas.

FIG. 7 shows a method for separating a vapor component from a carrier gas.

DETAILED DESCRIPTION

It will be readily understood that the components of the present invention, as generally described and illustrated in the Figures herein, could be arranged and designed in a wide variety of different configurations. Thus, the following more detailed description of the embodiments of the invention, as represented in the Figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of certain examples of presently contemplated embodiments in accordance with the invention.

Referring to FIG. 1, an inner chamber of a heat exchanger is shown at 100, as per one embodiment of the present invention. Inner chamber 102, located inside an outer chamber, is provided with coolant 112. Carrier gas 104 is provided to the outer chamber and passed across inner chamber 102. A vapor component of carrier gas 104 desublimate or condense onto outer surface 110 of inner chamber 102 as solid product 108. Vibration inducing device 106 is attached to inner chamber 102 and causes inner chamber 102 to vibrate. The vibration causes solid product 108 to fall from outer surface 110 of inner chamber 102, and solid product 108 can be collected while component-depleted carrier gas 114 is removed.

Referring to FIG. 2, an inner chamber of a heat exchanger is shown at 200, as per one embodiment of the present invention. Inner chamber 202, located inside an outer chamber, is provided with coolant 212. Carrier gas 204 is provided to the outer chamber and passed across inner chamber 202. A vapor component of carrier gas 204 desublimate or condense onto outer surface 210 of inner chamber 202 as solid product 208. Coolant 212 is provided by a pump at varying speeds, causing the inner chamber to flex or experience hammering. The flexing causes solid product 208 to fall from outer surface 210 of inner chamber 202, and solid product 208 can be collected while component-depleted carrier gas 214 is removed.

Referring to FIG. 3, an isometric cutaway view of a heat exchanger is shown at 300, as per one embodiment of the present invention. Outer chamber 302 is provided with carrier gas 304. Inner chamber 306, consisting of a series of tube bundles, is provided with coolant 312. Carrier gas 304 is passed across outer surface 310 of inner chamber 306. A vapor component of carrier gas 304 desublimate or condense onto outer surface 310 of inner chamber 304 as solid product 308. Coolant 312 is provided by a pump at varying speeds, causing inner chamber 306 to flex or experience hammering. The flexing causes solid product 308 to fall from outer surface 310 of inner chamber 306. Solid product 308 falls through hopper 314 into auger 316. Auger 316 carries solid product 308 out of the heat exchanger while carbon dioxide-depleted carrier gas 318 leaves the heat exchanger. In some embodiments, outer chamber 302 is provided with a vibration inducing device. The vibration inducing device causes outer chamber 302 to vibrate. As inner chamber 306 passes through the wall of outer chamber 302, the vibration propagates to inner chamber 306.

Referring to FIG. 4, an isometric cutaway view of a heat exchanger is shown at 400, as per one embodiment of the present invention. Outer chamber 402 is provided with dried combustion flue gas 404. Inner chamber 406, consisting of a series of corrugated tube bundles, is provided with coolant 412. Dried combustion flue gas 404 is passed across outer surface 410 of inner chamber 406. The carbon dioxide in carrier gas 404 desublimates onto outer surface 410 of inner chamber 406 as solid product 408. Coolant 412 is provided by a pump at varying pressures, causing the corrugated tube bundles of inner chamber 406 to expand or contract. The flexing causes solid product 408 to fall from outer surface 410 of inner chamber 404. Solid product 408 falls through hopper 414 into paddlewheel 416. Paddlewheel 416 carries solid product 408 out of the heat exchanger while carbon dioxide-depleted carrier gas 418 leaves the heat exchanger. In some embodiments, outer chamber 402 is provided with a vibration inducing device. The vibration inducing device causes outer chamber 402 to vibrate. As inner chamber 406 passes through the wall of outer chamber 402, the vibration propagates to inner chamber 406.

Referring to FIG. 5, a cutaway view of a heat exchanger is shown at 500, as per one embodiment of the present invention. Outer chamber 502 is provided with natural gas 504. Inner chamber 506, consisting of a series of corrugated tube bundles, is provided with coolant 512. Natural gas 504 is passed across outer surface 510 of inner chamber 506. The carbon dioxide in carrier gas 504 desublimates onto outer surface 510 of inner chamber 506 as solid product 508. Baffles 522 cause natural gas 504 to follow a tortuous path across inner chamber 506. Baffles 522 are slanted downward at an angle to cause solid product 508 to slide downward. Tube bundle 510 has vibration inducing device 518 attached, which causes inner chamber 506 to vibrate and flex. The flexing causes solid product 508 to fall from outer surface 510 of inner chamber 504. Solid product 508 falls through hopper 514 into auger 516. Auger 516 carries solid product 508 out of the heat exchanger while carbon dioxide-depleted carrier gas 520 leaves the heat exchanger.

Referring to FIG. 6, an isometric view of an inner chamber of a heat exchanger is shown at 600, as per one embodiment of the present invention. Inner chamber 602, located inside an outer chamber, is provided with coolant 612. Carrier gas 604 is provided to the outer chamber and passed across inner chamber 602. A vapor component of carrier gas 604 desublimate or condense onto outer surface 610 of inner chamber 602 as solid product 608. Inner chamber 602, comprising a flexible hose, is fed coolant 612 at a velocity that induces a generally sinusoidal undulation of the flexible hose, causing outer surface 610 to flex. The flexing causes solid product 608 to fall from outer surface 610 of inner chamber 602, and solid product 608 can be collected, while component-depleted carrier gas 614 is removed. In some embodiments, the flexible hose is situated to strike other flexible hoses or the outer chamber while undulating.

Referring to FIG. 7, a method for separating a vapor component from a carrier gas in a heat exchanger is disclosed at 700, as per one embodiment of the present invention. A carrier gas is provided to an outer chamber for cooling 701. A coolant is provided to an inner chamber, providing cooling to the carrier gas, causing a vapor component of the carrier gas to desublimate or condense onto an outer surface of the inner chamber, forming a solid product 702. A means for causing the inner chamber to flex is provided 703. The solid product falls from the outer surface of the inner chamber and is collected 704.

In some embodiments, the coolant pressure is varied rapidly by a pump operating at variable speeds, a valve rapidly opening and closing, or a combination thereof, causing the inner chamber to experience a hammering.

In some embodiments, the vapor component comprises water, carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, any hydrocarbon that has a higher freezing point than the temperature of the coolant, mercury, or combinations thereof. In some embodiments, the carrier gas comprises combustion flue gas, syngas, producer gas, natural gas, steam reforming gas, any hydrocarbon that has a lower freezing point than the temperature of the coolant, light gases, refinery off-gases, or combinations thereof. In some embodiments, the coolant comprises liquid nitrogen, ethane, methane, propane, refrigerants, and combinations thereof.

In some embodiments, the outer surface of the inner chamber comprises a material that inhibits adsorption of gases, prevents deposition of solids, or a combination thereof. In some embodiments, the material comprises ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, natural diamond, man-made diamond, chemical-vapor deposition diamond, polycrystalline diamond, or combinations thereof.

In some embodiments, the solid product is collected by a device comprising an auger, a conveyor belt, a roller, a paddlewheel, a bin, a bag, a chute, or a combination thereof. In some embodiments, the auger is attached to the outer chamber by a hopper. In some embodiments, the auger passes the solids product through an outlet that comprises a restriction that provides a back pressure, pressurizing the solids, the outlet feeding a melter, the melter producing a liquid product.

In some embodiments, the carrier gas is provided to the outer chamber through an outlet for removal of the solids product.

In some embodiments, the inner chamber comprises a tube bundle. In some embodiments, the outer chamber comprises baffles that direct the carrier gas across the tube bundle. In some embodiments, the heat exchanger comprises a shell and tube, brazed plate, aluminum plate, plate, plate and frame, plate and shell, spiral, or plate fin style heat exchanger.

In some embodiments, the inner chamber comprises a temperature sensor.

Combustion flue gas consists of the exhaust gas from a fireplace, oven, furnace, boiler, steam generator, or other combustor. The combustion fuel sources include coal, hydrocarbons, and biomass. Combustion flue gas varies greatly in composition depending on the method of combustion and the source of fuel. Combustion in pure oxygen produces little to no nitrogen in the flue gas. Combustion using air leads to the majority of the flue gas consisting of nitrogen. The non-nitrogen flue gas consists of mostly carbon dioxide, water, and sometimes unconsumed oxygen. Small amounts of carbon monoxide, nitrogen oxides, sulfur dioxide, hydrogen sulfide, and trace amounts of hundreds of other chemicals are present, depending on the source. Entrained dust and soot will also be present in all combustion flue gas streams. The method disclosed applies to any combustion flue gases. Dried combustion flue gas has had the water removed.

Syngas consists of hydrogen, carbon monoxide, and carbon dioxide.

Producer gas consists of a fuel gas manufactured from materials such as coal, wood, or syngas. It consists mostly of carbon monoxide, with tars and carbon dioxide present as well.

Steam reforming is the process of producing hydrogen, carbon monoxide, and other compounds from hydrocarbon fuels, including natural gas. The steam reforming gas referred to herein consists primarily of carbon monoxide and hydrogen, with varying amounts of carbon dioxide and water.

Light gases include gases with higher volatility than water, including hydrogen, helium, carbon dioxide, nitrogen, and oxygen. This list is for example only and should not be implied to constitute a limitation as to the viability of other gases in the process. A person of skill in the art would be able to evaluate any gas as to whether it has higher volatility than water.

Refinery off-gases comprise gases produced by refining precious metals, such as gold and silver. These off-gases tend to contain significant amounts of mercury and other metals.

Claims

1. A heat exchanger for separating a vapor component from a carrier gas comprising:

an outer chamber wherein the carrier gas is cooled, causing a vapor component of the carrier gas to desublimate or condense onto an outer surface of an inner chamber, forming a solid product;

the inner chamber wherein a coolant is passed to cool the carrier gas of the outer chamber; and,

a means for causing the inner chamber to flex, causing the solid product to fall from the outer surface of the inner chamber for collection.

2. The heat exchanger of claim 1, wherein the means for causing the inner chamber to flex comprise a vibration inducing device attached to a portion of the heat exchanger, varying coolant pressure, or combinations thereof.

3. The heat exchanger of claim 2, wherein the vibration inducing device comprises a piezoelectric actuator, ultrasound emitter, voice coil, linear resonant actuator, shaker, exciter, hydraulic actuator, solenoid actuator, blunt object, manual shaking, or a combination thereof.

4. The heat exchanger of claim 2, wherein the coolant pressure is varied and the inner chamber is constructed from expanding and contracting corrugated tubes, wherein varying the coolant pressure causes the corrugated tubes to expand and contract.

5. The heat exchanger of claim 2, wherein the coolant pressure is varied rapidly by a pump operating at variable speeds, a valve rapidly opening and closing, or a combination thereof, causing the inner chamber to experience a hammering.

6. The heat exchanger of claim 1, wherein the vapor component comprises water, carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, any hydrocarbon that has a higher freezing point than the temperature of the coolant, mercury, or combinations thereof, and the carrier gas comprises combustion flue gas, syngas, producer gas, natural gas, steam reforming gas, any hydrocarbon that has a lower freezing point than the temperature of the coolant, light gases, refinery off-gases, or combinations thereof.

7. The heat exchanger of claim 1, wherein the outer surface of the inner chamber comprises a material that inhibits adsorption of gases, prevents deposition of solids, or a combination thereof, the material comprising ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, natural diamond, man-made diamond, chemical-vapor deposition diamond, polycrystalline diamond, or combinations thereof.

8. The heat exchanger of claim 1, wherein the solid product is collected by a device comprising an auger, a conveyor belt, a roller, a paddlewheel, a bin, a bag, a chute, or a combination thereof, the device attached to the outer chamber by a hopper.

9. The heat exchanger of claim 1, wherein the inner chamber comprises a tube bundle and the outer chamber comprises baffles that direct the carrier gas across the tube bundle.

10. The heat exchanger of claim 1, wherein the inner chamber comprises a flexible hose that is fed the coolant at a velocity that induces a resonance in the flexible hose, causing the flexible hose to undulate in a sinusoidal manner.

11. A method for using the heat exchanger of claim 1 for separating a vapor component from a carrier gas in a heat exchanger comprising:

providing a carrier gas to an outer chamber wherein the carrier gas is cooled, causing a vapor component of the carrier gas to desublimate or condense onto an outer surface of an inner chamber, forming a solid product;

passing a coolant through the inner chamber to cool the carrier gas of the outer chamber; and,

providing a means for causing the inner chamber to flex, causing the solid product to fall from the outer surface of the inner chamber for collection;

whereby the vapor component is separated from the carrier gas.

12. The method of claim 11, wherein the means for causing the inner chamber to flex comprise a vibration inducing device attached to a portion of the heat exchanger, varying coolant pressure, or combinations thereof.

13. The method of claim 12, wherein the vibration inducing device comprises a piezoelectric actuator, ultrasound emitter, voice coil, linear resonant actuator, shaker, exciter, hydraulic actuator, solenoid actuator, blunt object, manual shaking, or a combination thereof.

14. The method of claim 12, wherein the coolant pressure is varied and the inner chamber is constructed from expanding and contracting corrugated tubes, wherein varying the coolant pressure causes the corrugated tubes to expand and contract.

15. The method of claim 12, wherein the coolant pressure is varied rapidly by a pump operating at variable speeds, a valve rapidly opening and closing, or a combination thereof, causing the inner chamber to experience a hammering.

16. The method of claim 11, wherein the vapor component comprises water, carbon dioxide, nitrogen oxide, sulfur dioxide, nitrogen dioxide, sulfur trioxide, hydrogen sulfide, hydrogen cyanide, water, any hydrocarbon that has a higher freezing point than the temperature of the coolant, mercury, or combinations thereof, and the carrier gas comprises combustion flue gas, syngas, producer gas, natural gas, steam reforming gas, any hydrocarbon that has a lower freezing point than the temperature of the coolant, light gases, refinery off-gases, or combinations thereof.

17. The method of claim 11, wherein the outer surface of the inner chamber comprises a material that inhibits adsorption of gases, prevents deposition of solids, or a combination thereof, the material comprising ceramics, polytetrafluoroethylene, polychlorotrifluoroethylene, natural diamond, man-made diamond, chemical-vapor deposition diamond, polycrystalline diamond, or combinations thereof.

18. The method of claim 11, wherein the solid product is collected by a device comprising an auger, a conveyor belt, a roller, a paddlewheel, a bin, a bag, a chute, or a combination thereof, the device attached to the outer chamber by a hopper.

19. The method of claim 11, wherein the inner chamber comprises a tube bundle and the outer chamber comprises baffles that direct the carrier gas across the tube bundle.

20. The method of claim 11, wherein the inner chamber comprises a flexible hose that is fed the coolant at a velocity that induces a resonance in the flexible hose, causing the flexible hose to undulate in a sinusoidal manner.