# US 8,771,401 B2 · Apparatus and process for the separation of gases using supersonic expansion and oblique wave compression > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 8,771,401 B2 - Document ID: US8771401B2 - Status: Granted - Kind: B2 - Application number: 13/208,784 - Filed: 2011-08-12 - Published: 2013-02-14 - Granted: 2014-07-08 - Earliest claimed: 2011-08-12 - Assignees: U.S. Department of Energy - Applicants: John G. VanOsdol - Inventors: John G. VanOsdol - Web page: https://patentgrep.com/patent/US8771401B2 ## CPC - F25J 3/066: {separation of nitrogen (from air F25J3/04, production of nitrogen in general C01B21/00)} - B01D 53/002: {by condensation} - C01B 32/55: Solidifying - F25J 3/067: {separation of carbon dioxide (production of carbon dioxide in general C01B32/00)} - B01D 2256/10: Nitrogen - B01D 2256/12: Oxygen - B01D 2257/504: Carbon dioxide - F25J 2205/10: using combined expansion and separation, e.g. in a vortex tube, "Ranque tube" or a "cyclonic fluid separator", i.e. combination of an isentropic nozzle and a cyclonic separator; Centrifugal separation - F25J 2205/20: using solidification of components - Y02C 20/40: of CO2 - Y02P 20/151: Reduction of greenhouse gas [GHG] emissions, e.g. CO2 - F25J: LIQUEFACTION, SOLIDIFICATION OR SEPARATION OF GASES OR GASEOUS {OR LIQUEFIED GASEOUS} MIXTURES BY PRESSURE AND COLD TREATMENT {OR BY BRINGING THEM INTO THE SUPERCRITICAL STATE (cryogenic pumps F04B37/08; gas storage vessels, gas holders F17; filing vessels with, or discharging from vessels, compressed, liquefied or solidified gases F17C; refrigeration machines, plants, or systems F25B)} - B01D: SEPARATION (separating solids from solids by wet methods B03B, B03D; by pneumatic jigs or tables B03B; by other dry methods B07; magnetic or electrostatic separation of solid materials from solid materials or fluids, separation by high-voltage electric fields B03C; centrifuges, vortex apparatus B04; presses per se for squeezing-out liquid from liquid-containing material B30B9/02; treatment of water C02F, e.g. softening by ion-exchange C02F1/42; {arrangements of air intake cleaners in gas turbine plants F02C7/05} ; arrangements or mounting of filters in air-conditioning, air-humidification or ventilation F24F13/28) - C01B: NON-METALLIC ELEMENTS; COMPOUNDS THEREOF; {METALLOIDS OR COMPOUNDS THEREOF NOT COVERED BY SUBCLASS C01C} - Y02C: CAPTURE, STORAGE, SEQUESTRATION OR DISPOSAL OF GREENHOUSE GASES [GHG] - Y02P: CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS ## Abstract The disclosure provides an apparatus and method for gas separation through the supersonic expansion and subsequent deceleration of a gaseous stream. The gaseous constituent changes phase from the gaseous state by desublimation or condensation during the acceleration producing a collectible constituent, and an oblique shock diffuser decelerates the gaseous stream to a subsonic velocity while maintain the collectible constituent in the non-gaseous state. Following deceleration, the carrier gas and the collectible constituent at the subsonic velocity are separated by a separation means, such as a centrifugal, electrostatic, or impingement separator. In an embodiment, the gaseous stream issues from a combustion process and is comprised of N2 and CO2. ## Claims ### Claim 1 A method for the removal of a gaseous constituent from a gas stream comprised of a carrier gas and the gaseous constituent, where the gas stream is at an initial temperature and an initial pressure, and where the carrier gas and the gaseous constituent comprising the gas stream are in a gaseous state at the initial temperature and the initial pressure, and where the gaseous constituent alters phase by desublimation or condensation at a higher temperature than the carrier gas at a given pressure, comprising: accelerating the gas stream to a specified supersonic velocity, thereby establishing the gas stream at an acceleration temperature and an acceleration pressure, where the acceleration temperature is less than the initial temperature and where the acceleration pressure is less than the initial pressure; directing the gas stream at the specified supersonic velocity to a diffuser inlet of an oblique shock diffuser, where the oblique shock diffuser is comprised of a compression corner and a diffuser profile; contacting the gas stream and the compression corner and allowing the compression corner and the diffuser profile to generate an oblique shock wave pattern in the oblique shock diffuser; decelerating the gas stream at the specified supersonic velocity to a subsonic flow at a subsonic velocity through a deceleration temperature-pressure profile by flowing the gas stream through the oblique shock wave pattern in the oblique shock diffuser, where the deceleration temperature-pressure profile is a plurality of pressure and temperature conditions experienced by the gas stream during the decelerating, and where the deceleration temperature-pressure profile originates at the acceleration temperature and the acceleration pressure and terminates at a deceleration temperature and a deceleration pressure at a diffuser outlet of the oblique shock diffuser, where the deceleration temperature is greater than the acceleration temperature and the deceleration pressure is greater than the acceleration pressure, and where the gaseous constituent crosses a phase boundary of the gaseous constituent as the gas stream transitions from the initial temperature and the initial pressure to the deceleration temperature and the deceleration pressure such that the gaseous constituent forms a collectable constituent, where the collectible constituent is a non-gaseous phase at the deceleration temperature and the deceleration pressure, and where the carrier gas is maintained in the gaseous state at the deceleration temperature and the deceleration pressure, such that the collectible constituent and the carrier gas comprise the subsonic flow at the diffuser outlet of the oblique shock diffuser; and transferring the subsonic flow from the diffuser outlet to a separation means, and separating the collectible constituent and the carrier gas using the separation means, thereby removing the gaseous constituent from the gas stream. ### Claim 2 (depends on 1) The method of claim 1 where the accelerating step comprises: porting the gas stream to a nozzle inlet of a supersonic nozzle, where the supersonic nozzle has a geometry such that when the gas stream is ported to the nozzle inlet at an inlet pressure, an inlet temperature, and an inlet mass flow rate, the supersonic nozzle acts to accelerate the gas stream such that the gas stream achieves the specified supersonic velocity at a nozzle outlet of the supersonic nozzle; and maintaining the nozzle outlet of the supersonic nozzle in fluid communication with the diffuser inlet of the oblique shock diffuser, such that the gas stream at the specified supersonic velocity is directed to the diffuser inlet of the oblique shock diffuser. ### Claim 3 (depends on 1) The method of claim 1 where the decelerating step comprises subjecting the gas stream to a converging diffuser profile following the contact between the gas stream and the compression corner, thereby increasing a pressure of the gas stream and thereby decreasing a velocity of the gas stream, and thereby subjecting the collectible constituent to at least some portion of the converging diffuser profile. ### Claim 4 (depends on 3) The method of claim 3 further comprising forming the collectible constituent in the non-gaseous phase during the accelerating step. ### Claim 5 (depends on 4) The method of claim 4 further comprising maintaining the deceleration temperature-pressure profile during the decelerating step such that the collectible constituent is in the non-gaseous phase at each of the plurality of pressure and temperature conditions experienced by the gas stream during the decelerating. ### Claim 6 (depends on 3) The method of claim 3 further comprising forming the collectible constituent during the decelerating the gas stream at the specified supersonic velocity to a subsonic flow step. ### Claim 7 (depends on 1) The method of claim 1 where the collectible constituent is a solid phase at the diffuser outlet. ### Claim 8 (depends on 7) The method of claim 7 where the gaseous constituent is CO2 and the carrier gas is N2. ### Claim 9 (depends on 8) The method of claim 8 where the gas stream is comprised of at least 8 wt % CO2 and at least 50 wt % N2. ### Claim 10 (depends on 9) The method of claim 9 where the specified supersonic velocity is at least Mach 3. ### Claim 11 A method for the removal of a gaseous constituent from a gas stream comprised of a carrier gas and the gaseous constituent, where the gas stream is at an initial temperature and an initial pressure, and where the carrier gas and the gaseous constituent comprising the gas stream are in a gaseous state at the initial temperature and the initial pressure, and where the gaseous constituent alters phase by desublimation or condensation at a higher temperature than the carrier gas at a given pressure, comprising: accelerating the gas stream to a specified supersonic velocity, thereby establishing the gas stream at an acceleration temperature and an acceleration pressure, where the acceleration temperature is less than the initial temperature and where the acceleration pressure is less than the initial pressure; directing the gas stream at the specified supersonic velocity to a diffuser inlet of an oblique shock diffuser, where the oblique shock diffuser is comprised of a compression corner and a diffuser profile, where the diffuser profile is a converging diffuser profile; contacting the gas stream and the compression corner and allowing the compression corner and the diffuser profile to generate an oblique shock wave pattern in the oblique shock diffuser; decelerating the gas stream at the specified supersonic velocity to a subsonic flow at a subsonic velocity through a deceleration temperature-pressure profile by flowing the gas stream through the oblique shock wave pattern in the oblique shock diffuser and subjecting the gas stream to the converging diffuser profile of the oblique shock diffuser, where the deceleration temperature-pressure profile is a plurality of pressure and temperature conditions experienced by the gas stream during the decelerating, and where the deceleration temperature-pressure profile originates at the acceleration temperature and the acceleration pressure and terminates at a deceleration temperature and a deceleration pressure at a diffuser outlet of the oblique shock diffuser, where the deceleration temperature is greater than the acceleration temperature and the deceleration pressure is greater than the acceleration pressure, and where the gaseous constituent crosses a phase boundary of the gaseous constituent as the gas stream transitions from the initial temperature and the initial pressure to the deceleration temperature and the deceleration pressure such that the gaseous constituent forms a collectable constituent, where the collectible constituent is a non-gaseous phase at the deceleration temperature and the deceleration pressure, and where the carrier gas is maintained in the gaseous state at the deceleration temperature and the deceleration pressure, such that the collectible constituent and the carrier gas comprise the subsonic flow at the diffuser outlet of the oblique shock diffuser, and thereby increasing a pressure of the gas stream and thereby decreasing a velocity of the gas stream, and thereby subjecting the collectible constituent to at least some portion of the converging diffuser profile; and transferring the subsonic flow from the diffuser outlet to a separation means, and separating the collectible constituent and the carrier gas using the separation means, thereby removing the gaseous constituent from the gas stream. ### Claim 12 (depends on 11) The method of claim 11 where the accelerating step comprises: porting the gas stream to a nozzle inlet of a supersonic nozzle, where the supersonic nozzle has a geometry such that when the gas stream is ported to the nozzle inlet at an inlet pressure, an inlet temperature, and an inlet mass flow rate, the supersonic nozzle acts to accelerate the gas stream such that the gas stream achieves the specified supersonic velocity at a nozzle outlet of the supersonic nozzle; and maintaining the nozzle outlet of the supersonic nozzle in fluid communication with the diffuser inlet of the oblique shock diffuser, such that the gas stream at the specified supersonic velocity is directed to the diffuser inlet of the oblique shock diffuser. ### Claim 13 (depends on 12) The method of claim 12 further comprising forming the collectible constituent in the non-gaseous phase during the accelerating step. ### Claim 14 (depends on 13) The method of claim 13 further comprising maintaining the deceleration temperature-pressure profile during the decelerating step such that the collectible constituent is in the non-gaseous phase at each of the plurality of pressure and temperature conditions experienced by the gas stream during the decelerating. ### Claim 15 (depends on 14) The method of claim 14 where the collectible constituent is a solid phase at the diffuser outlet, and where the separation means is a gas-solid separator. ### Claim 16 (depends on 15) The method of claim 15 where the gaseous constituent is CO2 and the carrier gas is N2. ### Claim 17 (depends on 16) The method of claim 16 where the gas stream is comprised of at least 8 wt % CO2 and at least 50 wt % N2. ### Claim 18 (depends on 17) The method of claim 17 where the specified supersonic velocity is at least Mach 3. ### Claim 19 (depends on 12) The method of claim 12 further comprising forming the collectible constituent during the decelerating the gas stream at the specified supersonic velocity to a subsonic flow step.