Patent EA-002780-B1 (EA)
Title: Method and apparatus for separation gas mixture components and liquefaction therefor
Inventor: ALFEROV VADIM IVANOVICH
IPC: F25J3/06
Filed: 1999-10-15
Abstract: 1. A method of liquefying a gas, the method comprising the steps of: (1) applying a swirl velocity to the gas; (2) passing the gas, with the swirl velocity/ through a nozzle having a nozzle  throat and a nozzle wall, and providing the gas with initial values of temperature and pressure, whereby, downstream from the nozzle throat, the gas adiabatically expands, the gas velocity increases, and the gas temperature drops, to promote the condensation of gas with formation of droplets; (3) passing the gas flow, with the swirl velocity, further through a working section axially aligned with the nozzle/ and, having a wall that provides an extension of the nozzle wall, whereby further adiabatic expansion and condensation of at least a portion of the gas flow occurs and droplets of condensed gas grow as a result of turbulent mixing; (4) permitting centrifugal effects generated by the swirl velocity to drive the droplets towards the wall of the working section, and providing a working section that is long enough for a majority of the condensed ga8 droplets to reach the wall of the working section; and (5) separating the condensed gas droplets from remaining gas in the gaseous state at least adjacent the wall of the working section. 2. A method as claimed in claim 1, which includes separating condensed liquid from the gas flow in the working section at a location spaced a distance L from the dew point of the liquefied gas component, where L= V x τ, where V is the speed of the gas flow at the outcome of the nozzle and τ is the time taken for condensed droplets of gas to travel from the axis of the nozzle to a wall of tile working section. 3. A method as claimed in claim 1 or 2, which includes applying a swirl component to the gas such that the gas is subject to centrifugal acceleration of greater than 10/000g near the wall of the working section, where g is acceleration of free fall. 4. A method as claimed in claim 1, 2 or 3, which includes separating condensed droplets through an annular slot. 5. A method as claimed in claim I, 2 or 3, which includes separating condensed droplets through perforations. 6. A method as claimed in claim 1, which includes applying the method to a gas comprising a plurality of separate gaseous components having different properties, and the method further comprising adiabatically expanding the gas such that at least two gaseous components commence condensation at different axial locations downstream from the nozzle throaty to form the droplets and separating out the droplets of these gaseous components independently from each other gaseous component. 7. A method as claimed in claim 6, which includes collecting the condensed droplets of each gaseous component through perforations in a wall of working section. 8. A method as claimed in claim 6, which includes collecting the droplets of each condensed gaseous component through a respective annular slot. 9. A method as claimed in claim 8, which includes providing each annular slot at a location which is a distance Li from the axial location at which a corresponding gaseous component condenses, where Li is determined by the relationship Li = Vi x τi, where Li is the distance between the dew point of the i-th gas component to a location at which the i-th gaseous component is separated; Vi is the speed of the gas flow at the dew point of the i-th gaseous component and τi is the time for droplets of the i-th gaseous component to travel from die axis of the nozzle to the working section wall. 10. A method as claimed in any of claims 6 to 9 wherein the swirl component or velocity applied to the gas flow is such as to create a centrifugal acceleration of at least 10000g. 11. A method as claimed in any of claims 6 to 9 which includes applying the method to natural gas including methane, ethane, propane and butane as its main components. 12. A method as claimed in any one of claims 6 to 11, which includes providing the gaseous components at partial pressures selected such that, for one component having a lower temperature of condensation at atmospheric pressure than the temperature of condensation at atmospheric pressure of another component, said one component condenses first to form droplets containing at least part of said other component dissolved therein, and the method including separating said droplets from the gas. 13. A method as claimed in any one of claims 6 to 12 which includes applying the method to separation of methane and ethane. 14. A method as claimed in any one of claims 1 to 13, which includes in step (3) generating a substantially sonic velocity in the gas close to the nozzle throat, and causing the gas to expand supersonically in the working section. 15. An apparatus for liquefying a gas, the apparatus comprising: (1) means for imparting a swirl component of velocity to a gaseous flow; (2) downstream from said swirl generation means a nozzle comprising a convergent nozzle portion connected to the swirl generation means, a nozzle throat and a divergent working section, (3) axially aligned with the nozzle throat and having a wall with a divergence angle chosen to compensate for growth of a boundary layer, whereby in use/ the gas adiabatically expands downstream from the nozzle throat in the working section to cause condensation of at least some of the gas, thereby generating droplets of condensed gas; and (4) a separation means connected to the working section for separating condensed droplets from the gas. 16. An apparatus as claimed in claim 15, wherein the separation means of the nozzle includes perforations for separating out gas droplets. 17. An apparatus as claimed in claim 15, wherein the separation means includes at least one annular slot for separating out droplets of condensed gas. 18. An apparatus as claimed in claim 17, wherein the separation means includes a plurality of annular slots axlally spaced along the working section, for separating out droplets of different condensed gaseous components, for enabling the separation of different gaseous components of a gas mixture. 19. An apparatus as claimed in claim 18, wherein each of the annular slots is located a distance Li from the axial location at which a corresponding gaseous component condenses, where Li is determined by the relationship Li = Vi x τi, where Li is the distance between the dew point of the i-th gas component to a location at which the i-th gaseous component is separated; Vi is the speed of the gas now at the dew point of the i-th gaseous component and τi is the time for droplets of the i-th gaseous component to travel from me axis of the nozzle to a wall of the working section. 20- An apparatus as claimed in any one of claims 15 to 19, wherein the swirl generation means is capable of generating a swirl velocity which generates a centrifugal acceleration equal to or greater than 10000g. 21. An apparatus as claimed In any one of claims 15 to 20, including means for supplying gas at a sufficient pressure to generate a supersonic expansion in the working section. 22. An apparatus as claimed in claim 21, wherein the nozzle includes a divergent portion extending between the nozzle throat and the working section, for initial expansion and acceleration of the gas to supersonic velocities. 23. An apparatus as claimed in any one of claims 15 to 22, which includes a diffuser body located downstream from the working section, for recovering kinetic energy as increased pressure. 24. An apparatus as claimed in claim 23, which includes an annular slot extending around the diffuser body, for separation of liquid droplets, which annular slot includes an inner leading edge, wherein paid inner leading edge is provided in the diffuser body. 25. An apparatus as claimed in claims 23 or 24, wherein the diffuser body defines a supersonic diffuser, an intermediate portion and a subsonic diffuser. 26. An apparatus as claimed in claim 25, wherein the subsonic diffuser includes means for removing the swirl component of the velocity and recovering the rotational kinetic energy as axial kinetic energy, thereby to enable conversion of the axial kinetic energy into increased pressure.