GB1581728A

GB1581728A - Countercurrent contakt and separation of liquid and gaseous phases

Info

Publication number: GB1581728A
Application number: GB7172/77A
Authority: GB
Original assignee: Caribbean Properties Ltd
Current assignee: Caribbean Properties Ltd
Priority date: 1977-02-21
Filing date: 1977-02-21
Publication date: 1980-12-17
Also published as: FR2380804A1; DE2807221A1; FR2380804B1; AU3349378A; ZA78989B; JPS6127081B2; AU516312B2; JPS53103977A

Description

(54) COUNTERCURRENT CONTACT AND SEPARATION OF LIQUID AND GASEOUS PHASES (71) We, CARIBBEAN PROPERTIES LIMITED, a company organised under the laws of the Cayman Islands, British West Indies, of P.O. Box 514, Grand Cayman, British West Indies, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement: This invention relates to a process and an apparatus for the continuous countercurrent contact of a liquid phase with a gaseous phase, and their subsequent separation from one another. Such contact may involve heat exchange, one or more chemical reactions or the physical transfer of one or more constituents from either phase into the other.

Since any interaction between the two phases depends upon their degree of physical contact with one another, the rate of such interaction will become a direct function of the area of liquid surface (or interface) exposed to the gaseous phase per unit of time. For this reason gas scrubbers, absorbers, evaporators, cooling towers, distillation columns and other types of apparatus requiring such interaction are frequently designed to augment the area of liquid surface (or interface) so exposed either by dispersing the liquid phase into the gaseous phase or by bubbling the gaseous phase through the liquid phase.

The effective capacity of such apparatus will ultimately be limited by its ability to separate the respective phases from one another after contact. The finer the droplets sprayed into the gaseous phase, the more susceptible do they become to entrainment by the gas stream. When the gaseous phase is bubbled through the liquid phase, not only can the bubbles carry the liquid phase into the gas stream as a mist but the liquid phase can also entrap the gas bubbles in the form of a foam.

This invention makes it possible not only to supress the tendency toward such entrainment in either phase but also to separate existing suspensions of either phase from the other phase by providing a process for the continuous contact of a liquid phase with a gaseous phase and their subsequent separation from one another, the process comprising (a) introducing the liquid phase into a first conduit having a generally circular transverse section and a central longitudinal axis the conduit being open at one end to provide an outlet for the liquid phase therefrom, the outlet being in the form of a central orifice with a circular rim in a plane generally perpendicular to the longitudinal axis of the conduit, (b) directing the liquid phase to flow through the first conduit generally toward and through the said central circular orifice, (c) spinning the liquid phase in the first conduit about the longitudinal axis thereof fast enough to form the liquid phase flowing through the central circular orifice into a generally continuous annular spinning liquid curtain connecting the first conduit with an overlapping coaxial second conduit, the second conduit also having a generally circular transverse section, thereby providing a generally annular space between the two interlapped conduits, (d) introducing the gaseous phase into the annular space between the two interlapped conduits, (e) directing the gaseous phase to flow through the said annular space in a path surrounding, but generally in the same axial direction as, the path of the liquid phase flowing through the first conduit, whereby the gaseous phase must pass through the generally continuous annular spinning liquid curtain connecting the two interlapped conduits in order to occupy an inner space surrounded by the annular spinning liquid curtain, (f) withdrawing the gaseous phase from the said inner space, and (g) separately withdrawing the liquid phase from the second conduit.

Because the gaseous phase is made to bubble through a generally continuous liquid curtain before it can pass through the orifice, the centrifugal acceleration of the liquid phase, which is near its maximum at the edge of the orifice, will tend to supress the entrainment of mist droplets by the gas bubbles escaping radially inward from the inner surface of the spinning liquid curtain.

Mist droplets previously carried in suspension by the gaseous phase will also tend to be captured by the luquid phase during their flow through the spinning liquid curtain. The addition of a wetting agent to reduce the surface tension of the liquid phase will help to maintain the continuity of the spinning liquid curtain as its thickness is reduced in a radially outward direction and will enable it better to wet particulate matter suspended in the gaseous phase as the gaseous phase is bubbled through it.

The centrifugal acceleration of the spinning liquid curtain will also diminish the entrainment of foam by the liquid phase while previously entrained foam will be carried off by the gaseous phase as it bubbles through the thin liquid curtain.

This invention also provides an apparatus for the continuous contact of a liquid phase with a gaseous phase and their subsequent separation from one another, the apparatus comprising (a) a first conduit having a generally circular transverse section and a central longitudinal axis, the conduit being open at one end to provide an outlet for the liquid phase therefrom, the outlet being in the form of a central orifice with a circular rim in a plane generally perpendicular to the longitudinal axis of the conduit, (b) means for introducing the liquid phase into the first conduit and for directing the liquid phase to flow through the conduit generally toward and through the said central circular orifice, (c) a second conduit having a generally circular transverse section, the second conduit being coaxial with the first conduit and surrounding the central circular orifice, whereby the two conduits interlap to define an annular space therebetween, (d) means for spinning the liquid phase in the first conduit about the longitudinal axis thereof fast enough to form the liquid phase flowing through the central circular orifice into a generally continuous annular spinning liquid curtain connecting the first conduit with the second conduit.

(e) means for introducing the gaseous phase into the annular space between the two interlapped conduits, (f) means for directing the gaseous phase to flow through the said annular space in a path surrounding, but generally in the same axial direction as, the path of the liquid phase flowing through the first conduit, whereby the gaseous phase must pass through the generally continuous annular spinning liquid curtain connecting the two interlapped conduits in order to occupy an inner space surrounded by the annular spinning liquid curtain, (g) an outlet for the gaseous phase from the said inner space, and (h) a separate outlet for the liquid phase from the second conduit.

The partition preferably comprises a central funnel, preferably in the shape of a frustum of an inverted hollow cone coaxial with the conduit, with a circular internal crosssection which converges downward into the lower chamber to form the orifice at its throat.

In a preferred embodiment, the said longitudinal axis is vertical, and the first conduit has an inlet defined by a generally horizontal central circular orifice provided in a partition which divides the apparatus into an upper chamber and a lower chamber. For convenience, the following description is principally with reference to that preferred embodiment.

The means for introducing the liquid phase and withdrawing the gaseous phase will normally comprise an inlet for the liquid phase and an outlet for the gaseous phase but, for certain applications, other means can serve the first of these functions. For example, where the vapour of the liquid phase constitutes all or part of the gaseous phase, a cooling coil or jacket around the upper chamber could condense the vapour into the liquid phase, thus introducing the liquid phase into the upper chamber without the necessity for a separate inlet for the liquid phase.

The means for introducing the gaseous phase and withdrawing the liquid phase will normally comprise an inlet for the gaseous phase and an outlet for the liquid phase but, for certain applications, other means can also serve the first of these functions. For example, where the gaseous phase is the vapour of one of the constituents of the liquid phase or where a gas or a more volatile liquid is dissolved or colloidally dispersed in the liquid phase, a heating coil or jacket around the lower chamber could drive the gas or vapour from the liquid phase into the gaseous phase, thus introducing the gaseous phase into the lower chamber without the necessity for a separate inlet for the gaseous phase.

When two or more units of the apparatus are connected in series with one another, the upper chamber of one unit can serve as the lower chamber of the unit next above it and the orifice can serve the first unit both as the inlet for its liquid phase and the outlet for its gaseous phase while, for the unit next above it, the same orifice would be both the inlet for its gaseous phase and the outlet for its liquid phase.

The means for spinning can be one, or any combination, of well known means such as a helical vane or channel, means for the tangential introduction of either the gaseous or the liquid phase (or both), or a rotating fan or impeller. The velocity of spin of both phases can be augmented, without significant effect upon their longitudinal velocities, by the tangential introduction, preferably into the lower chamber, of the vapour of a constituent of the liquid phase at a high enough pressure through one or more appropriate nozzles.

The means for directing the flow will normally comprise one or more baffles or vanes to prevent the gaseous phase in the lower chamber from entering the bottom of the orifice without first having had to pass through the generally continuous curtain of the spinning liquid phase which will screen the gap between the baffle and the bottom of the orifice. Since both phases will be spinning at approximately the same rotational velocity, the only significant relative motion between them will be their relatively slow generally countercurrent velocity in the radial and longitudinal directions.

Each of these baffles will preferably be in the shape of the frustum of an inverted hollow cone coaxial with and surrounding a funnel of the same shape conveying the spinning liquid phase downward from the upper chamber to the orifice formed by the throat of the funnel. The gaseous phase from the lower chamber will enter the passage between the two cones at the top of the outer cone and will have to pass through the generally continuous liquid cascade spinning outward from the orifice at the bottom of the inner cone before it can enter the orifice and rise through the inner cone into the upper chamber. Meanwhile, the spinning liquid phase drains down the inner wall of the outer cone toward a liquid outlet at the bottom of the outer cone.

Whenever a single unit of apparatus cannot bring the interaction between the gaseous and liquid phases to the desired degree of completion, additional units can be connected in series with one another. The fresh gaseous feed could enter the lower chamber of the first unit of such a series in which the liquid feed into its upper chamber could be the effluent liquid discharged from the lower chamber of the second unit, while the fresh liquid feed could enter the upper chamber of the last unit of the series, in which the gaseous feed into its lower chamber could be the gas exhausted from the upper chamber of the next to last unit. A similar arrangement can be used when the apparatus is to serve for the continuous fractional distillation of miscible liquids. The mixture would be continuously introduced into an intermediate unit, the more volatile fraction exhausted from the upper chamber of the last unit in the vapour phase, while the less volatile fraction would be continuously discharged from the lower chamber of the first unit in the liquid phase.

When the primary function of the liquid phase is as a scrubbing medium for the extraction of soluble gases or other constituents from the gaseous phase, it is often advantageous for it to carry one or more surfactants or reagents capable of wetting, neutralizing or otherwise reacting with specific solid, liquid or gaseous constituents, borne by the gaseous phase. For this purpose, the presence of a wetting agent to reduce the surface tension of the liquid phase provides the extra advantage that it helps to maintain the continuity of the spinning liquid curtain formed by the liquid phase as it grows progressively thinner during its flow radially outward into the lower chamber after emerging from the lower edge of the orifice.

Mist droplets suspended in the gaseous phase can best be removed in this apparatus when they are soluble in, and preferably miscible with, the liquid phase. Suspended solid particles can similarly be removed from the gaseous phase in this apparatus by converting them to such mist droplets by the condensation of the vapour of the liquid phase upon particulate nuclei suspended in the gaseous phase. This vapour can either be admitted into the gaseous phase through an appropriate inlet or evaporated from the liquid phase and recondensed closer to the axis of spin when the velocity of spin is fast enough to provide the radial temperature gradient required. Further details of this may be found in our U.K. Patent Specification No.

1,445,978. When the spinning mist droplets encounter the generally continuous curtain formed by the spinning liquid phase emerging from the lower edge of the orifice they tend to become part of the liquid curtain spinning radially outward while the relatively mist-free gaseous phase continues its inward motion toward the orifice through which it subsequently rises into the upper chamber.

The particulate nuclei upon which the vapour condenses to form these mist droplets are thereby separated from the scrubbed gaseous phase and carried off with the effluent liquid phase discharged from the lower chamber.

Foams can also be broken in this apparatus if they are continuously introduced into the upper chamber through the inlet for the liquid phase, preferably at a temperature high enough to reduce the viscosity of the liquid phase to an appropriate level. The high centrifugal acceleration achievable in the vortex at the orifice will tend to release the entrapped gaseous phase and permit it to escape radially inward from the inner surface of the spinning liquid phase. The release of the foam will be accelerated by the continuous introduction into the lower chamber of a free supply of the gaseous phase, which will help to free the entrapped gases as it bubbles through the spinning liquid curtain.

Figures 1 and 3 each show, in partly schematic form, partly cut away vertical elevations of two embodiments of apparatus according to the invention. Figure 2 shows, on a larger scale and in greater detail, a partly cut away vertical elevation of a pair of the funnels, together with the helical guide between them, depicted on a smaller scale in Figure 1.

Referring to Figure 1, the apparatus comprises a generally cylindrical wall 2 defining a conduit 1 with a generally vertical longitudinal axis. The conduit 1 is divided into a lower chamber 3 and an upper chamber 4 by a generally transverse circular partition 5, the center of which is formed into a funnel 6, in the shape of the frustum of an inverted hollow cone, open at its throat 7 to provide a horizontal central circular orifice which becomes the sole means of communication between the two chambers.

The upper end of the upper chamber 4 is closed by the top 8, except for an effluent gas outlet 9 which penetrates the center of the top 8 and extends upward therefrom through a gaseous phase throttle valve 12.

One or more liquid phase inlets 10 are mounted tangentially to the cylindrical wall 2 and are directed therethrough into the upper chamber 4 in a generally horizontal direction. Each inlet 10 is preferably provided with a nozzle or orifice 11 to accelerate the velocity of the incoming liquid phase and a liquid feed valve 13 to regulate its rate of flow into the upper chamber 4. One or more of the inlets 10 can serve for the introduction of reagents or surfactants into the liquid phase.

A rotating impeller can optionally be installed in the upper chamber 4 as an alternative or supplementary means of spinning the liquid phase around its vertical longitudinal axis at a higher peripheral speed than that resulting from its optimum rate of flow through the tangential inlets 10. The impeller illustrated comprises a ring of vertical blades 20 secured to each other at their upper and lower ends by annular collars or yokes 18 and 19 respectively. The upper annular collar 18 is connected by radial spokes 17 to a vertical shaft 21. coaxial with the conduit 1 which extends through the center of the top 8 from the drive 16.

Below the partition 5, a gaseous phase inlet 24 is mounted tangentially to the wall 2 and directed therethrough into the lower chamber 3 in the same direction as the liquid phase inlets 10.

For certain applications, as in the scrubbing of particulate matter from the gaseous phase (see our U.K. Patent Specification No,1,445,978), one or more vapour inlets 37 can also be mounted tangentially to the wall 2 and directed therethrough into the lower chamber 3 in the same direction as the gaseous phase inlet 24. There they can serve both to saturate the gaseous phase with vapour and to accelerate its velocity of spin without increasing its rate of flow in a longitudinal direction. Each inlet 37 would normally be connected through a separate vapour feed valve 38 and an appropriate nozzle 39 to control the rate of flow of the incoming vapour and to convert its pressure into velocity.

A similar additional inlet 44 (controlled by a valve 45) could also be installed in the gaseous phase inlet 24 in the form of an ejector or a venturi scrubber 25, through which either a vapour or an evaporable liquid could be intimately mixed with the incoming gaseous phase to wet suspended particulate matter, especially by condensation thereupon from the vapour phase.

The lower end of the lower chamber 3 is closed by the bottom 14 which is preferably dished upward with its center above its outer edge, which is penetrated by a sludge outlet 26 extending outward and downward through a sludge valve 27.

The center of the bottom 14 is penetrated by a funnel 15, generally identical to and coaxial with the funnel 6, which converges downward from its circular mouth 33 at the center of the bottom 14 to its circular throat 34, leading through an effluent liquid outlet 22 to an effluent liquid valve 23. A liquid overflow line 35.connects the sludge outlet 26 with the effluent liquid outlet 22 through the liquid overflow valve 36.

The apparatus can be built so that the space between the outside surface of the funnel 6 and the inside surface of the funnel 15 is narrow enough to permit the formation of a generally continuous liquid curtain 41 by the descending liquid phase as it spins outward and downward from the lower edge of the throat 7 to screen the outlet from the passage between the two funnels through which the spinning gaseous phase is made to flow inward and downward from the lower chamber 3 before it can rise through the throat 7 toward the upper chamber 4.

However, as shown in Figure 1, the capacity and effectiveness of the apparatus can be increased and the longitudinal velocity of the gaseous phase passing through the spinning liquid curtain 41 reduced by increasing the distance between the funnels 6 and 15 and inserting between them a number of generally identical frusto-conical funnels 28 to provide an equal number of additional parallel passages 43 through which the gaseous phase can flow from the lower chamber 3 through an equal number of additional liquid curtains 41 on its way to the upper chamber 4. Thus the distance between any two adjacent funnels can be kept short enough to maintain the continuity of the spinning liquid curtains 41 across the passages 43 between the funnels while the total area across all the passages can be increased to watever extent is required to reduce the downward velocity of the gaseous phase emerging from the passages 43 to its optimum level. It is preferable for the vertical length of each of the funnels 28 to be slightly longer than that of the one immediately above it in order to make the diameter of each of their throats 31 progressively narrower as they approach the funnel 15.

Each of the funnels 28 is separated from the funnel next above it by one or more spiral or helical guides 29. The pitch of each of the guides 29 preferably diminishes progressively downward to provide convergent helical passages 43 with nearly horizontally directed outlets through which the gaseous phase can be made to spin faster and faster as it flows from the lower chamber 3 between the funnels in a generally downward and inward direction from the mount 30 of one funnel 28 toward the throat 31 of the funnel next above it. Each guide 29 may either be an integral part of a funnel 28 or a separate strip, preferably of a foamed or hollow elastomer, or a rope of flexible fibers secured between each pair of adjacent funnels.

Figure 2 illustrates, on a larger scale, and in greater detail, an adjacent pair of funnels 28, showing their mouths 30, their throats 31, the helical guide 29 between them and the liquid curtain 41 spinning outward and downward from the lower edge of the throat 31 of the upper funnel across the passage 43 between the two funnels to the inner surface of the lower funnel.

A cylindrical baffle 42, coaxial with the conduit 1, is shown in Figure 1 extending downward into the lower chamber 3 from the lower surface of the partition 5. It can serve both to distribute the flow of the gaseous phase more nearly equally among the passages 43 and to keep centrifugally separable particulate matter away from them.

In operation, the liquid phase is introduced continuously into the upper chamber 4 through the liquid phase inlet 10 and the orifice 11 at a rate controlled by the liquid feed valve 13. Because of the tangential configuration of the liquid phase inlet 10 and the increase in the inlet velocity induced in the liquid phase by the orifice 11, the incoming liquid phase will be directed along the inside of the wall 2, against which it will spin around the longitudinal vertical axis of the upper chamber 4 fast enough to form a free vortex with a surface 40 approaching the vertical at the throat 7.

If the.inlet velocity of the liquid phase emerging from the orifice 11 is too low to spin the liquid phase in the upper chamber 4 fast enough by itself, it can be made to spin faster by the rotation of the impeller blades 20, which would otherwise not be required.

After enough of the liquid phase has been introduced into the upper chamber 4 to narrow the inner diameter of the vortex surface 40 to that of the throat 7, the spinning liquid phase will overflow the edge of the throat 7, and spin radially outward and downward across the passage 43 between the outer surface of the funnel 6 and the inner surface of the highest of the funnels 28 in the form of generally continuous annular liquid curtain 41 which screens the outlet of the passage 43.

The descending liquid phase continues to spin along the inner surface of the highest of the funnels 28 along which it continues its descent until it overflows its throat 31 and spins radially outward and downward to form a second generally continuous liquid curtain 41 across the outlet of the passage 43 between the highest and next highest of the funnels 28.

The spinning liquid phase continues downward to overflow the throats 31 of successively lower funnels 28 and to form generally continuous liquid curtains 41 across the outlets of each of the passages 43 between them until it finally overflows the throat 34 of the funnel 15 and is continuously discharged through the effluent liquid outlet 22 at a rate regulated by the effluent liquid valve 23.

Meanwhile - the gaseous phase is introduced continuously through the gaseous phase inlet 24 into the lower chamber 3 at a rate controlled by the gaseous phase throttle valve 12. Because of the tangential configuration of the gaseous phase inlet 24 the gaseous phase is spun around the vertical longitudinal axis of the lower chamber 3 in the same direction as the spinning liquid phase. If its initial velocity of spin is not fast enough, it can be accelerated by the continuous tangential introduction of vapour at a higher velocity through one or more vapour inlets 37 and their appropriate nozzles 39 at rates controlled by their vapour feed valves 38. The vapour can either be that of one of the constituents of the liquid phase or another condensible vapour or gas either soluble in the liquid phase or which will react in the apparatus to form one or more products which are so soluble.

When the apparatus is to serve as a scrubber to separate suspended particulate matter from the gaseous phase, it can be made more effective if the weight of those solid particles which are not heavy enough to be readily separated centrifugally is first augmented by their transformation into mist droplets through the condensation upon their sur faces of the vapour of one of the constituents of the liquid phase. This can be accomplished in the lower chamber 3 by supersaturating the spinning gaseous phase there with this vapour by introducing it in the vapour phase either through a vapour inlet 37 or into the gaseous phase inlet 24 through the ejector 25. The same result can be achieved by evaporating it from the liquid phase in the relatively warmer peripheral portion of the spinning gaseous phase in the lower chamber 3 and condensing it from the vapour phase upon the suspended particles as they become cooled below the dew point by the adiabatic expansion of the gaseous phase as it is being accelerated during its radially inward flow both in the free vortex and the convergent helical passages 43. The liquid phase to be evaporated for this purpose is preferably introduced into the gaseous phase inlet 24 through the venturi scrubber 25, which would also serve to wet the larger particles and permit them to be separated centrifugally in the lower chamber 3, but could alternatively be introduced directly into the peripheral portion of the lower chamber 3 through a vapour inlet 37, preferably at a higher temperature than that introduced into the upper chamber 4 through a liquid phase inlet 10.

The suspended particulate matter that is heavy enough to be separated centrifugally will be spun against the wall 2, along which it will fall, together with part of the liquid phase either condensed within or introduced into the lower chamber 3, toward the sludge outlet 26, where the heavier sludge will be removed through the sludge valve 27 while the excess liquid phase will overflow through the liquid overflow line 35 into the effluent liquid outlet 22 at a rate regulated by the liquid overflow valve 36.

Meanwhile, the spinning gaseous phase, saturated with the vapour phase and carrying both suspended mist droplets and unwet particulate matter not heavy enough to be centrifugally separated, flows downward from the gaseous phase inlet 24 to a level below that of the lower edge of the cylindrical baffle 42 before flowing in a generally radially inward direction toward the mouths 30 of the funnels 28, where it enters the convergent helical passages 43 formed by the guides 29 between the funnels 28. Here its velocity of spin increases to a maximum and the consequent generally adiabatic expansion reduces its temperature to condense vapour both upon existing mist droplets and previously unwet particulate matter until it is forced to pass through the generally continuous liquid curtains 41, which screen the outlets of the passage 43, before it can rise through the throat 7 into the upper chamber 4. There it continues to spin in contact with the surface 40 of the spinning vortex of the coldest freshest liquid before finally being discharged through the effluent gas outlet 9 at a rate controlled by the gaseous phase throttle valve 12.

Since the velocity of spin and centrifugal acceleration of both the gaseous and liquid phases are at their maximum at the outlets of the helical passages 43 where the gaseous phase passes through the generally continuous liquid curtains 41, while the relative motion in a circumferential direction between the gaseous and liquid phases is comparatively insignificant, the entrainment of mist by the gaseous phase breaking through the liquid curtain 41 can be prevented so long as the centrifugal force applied to the inner surface of each spinning liquid curtain 41 is kept greater than the frictional drag upon it by the escaping gaseous phase. By regulating the flow of the gaseous phase through the gaseous phase throttle valve 12, its velocity of escape from the spinning surfaces of the liquid curtains 41 can be maintained at a level where not only no entrainment of mist occurs but mist droplets and even previously unwet particulate matter already suspended in the gaseous phase are captured and carried away from it by the spinning liquid phase.

For the same reason foams already in suspension in the liquid phase are broken up in th lower end to enable it to be connected to the upper end of the highest of the cylindrical members 102, is so connected by bolts 104.

The upper end of the cap 116 is closed by the top 108, except for an effluent gas outlet 109, which penetrates the center of the top 108 and extends upward therefrom through a gaseous phase throttle valve 112. The cap 116 is also provided with means for introducing the liquid phase, the nature of which depends upon the specific use for which the apparatus is designed.

For most purposes these means will take the form of a liquid phase inlet 110, mounted tangentially to the cylindrical wall of the cap 116 and directed therethrough horizontally into the upper part of the conduit 101. It is preferably mounted to embrace that wall and make it the latter part of the inner wall of the inlet 110, the outer wall of which forms a volute converging with it at the narrow vertical slot 111 which penetrates the wall of the cap 116 and thus serves as the throat of a spiral convergent nozzle to accelerate the velocity of the liquid phase introduced through the liquid feed valve 113.

Where the apparatus is designed as a fractionating column and no such liquid phase inlet is required, these means can be provided in the form of a cooling jacket 126, cooled by the flow of a liquid coolant, which will serve as a reflux condenser or dephlegmator and introduce the liquid phase into the cap 116 by condensing the less voltatile fraction from the vapour phase before the more volatile fraction is discharged through the effluent gas outlet 109.

At the lower end of the conduit 101, a sump 115, which is a hollow member similar to the cap 116 except that it is provided with a flange 103 only at its upper end to enable it to be connected to the lower end of the lowest of the cylindrical members 102, is so connected by bolts 104. The lower end of the sump 115 is closed by the bottom 114, except for an effluent liquid outlet 122 which penetrates the center of the bottom 114 and extends downward therefrom through an effluent liquid valve 123.

Where the apparatus is to serve as a distillation column, the sump 115 is provided with a heating jacket 125, through which a heating fluid is circulated in order to vapourize the more volatile fraction of the liquid phase before the less volatile fraction is discharged through the effluent liquid outlet 122.

A gaseous phase inlet 124 is mounted tangentially to the wall of the lowest of the cylindrical members 102 and directed therethrough horizontally into the conduit 101 in the same direction as the liquid phase inlet 110. It preferably takes a similar form to the inlet 110, embracing the wall of the member 102 with a volute converging with it at the narrow vertical slot 127 which penetrates the wall and thus serves as the throat of a spiral convergent nozzle to accelerate the velocity of the incoming gaseous phase.

One or more vapour inlets 137 may also be mounted tangentially to the wall of one or more intermediate cylindrical members 102 and directed therethrough horizontally into the conduit 101 in the same direction as the liquid phase inlet 110 and the gaseous phase inlet 124. Where the apparatus is to serve as a distillation column, one such inlet 137 will be required for the introduction of the materials to be distilled. Where the apparatus is to be used for the scrubbing of particulate matter from the gaseous phase, the introduction of the vapour of one of the constituents of the liquid phase into the conduit 101 through one or more vapour inlets 137 can serve both to accelerate the spinning of the gaseous phase without speeding up its longitudinal velocity and to wet suspended particulate matter by supersaturating the gaseous phase with that vapour. The form and configuration of the vapour inlet 137 may either be similar to those for the liquid phase inlet 110 and the gaseous phase inlet 124 (as shown in Fig. 3) or, where supersonic velocities are required, provided with convergent/divergent nozzles as in the inlet 37 shown in Fig. 1.

Between each pair of flanges 103 is bolted a transverse partition 105, each of which comprises a central funnel 106 in the shape of the frustum of an inverted hollow cone, open at the throat 107 to form a generally horizontal circular orifice which provides the sole communication between the respective chambers thus formed above and below each such partition 105.

Mounted coaxially just below each of the funnels 106 is a generally identical funnel 128, open at both ends (the mouth 130 and the throat 131), which serves as a baffle to guide the gaseous phase through the curtain 141 of liquid spinning outward and downward from the throat 107. Each funnel 128 is secured to the funnel 106 immediately above it by one or more helical guides 129 (like the helical guides 29 illustrated in Figure 2) to provide one or more helical passages 143 between the two funnels from the mouth 130 of the funnel 128 to the throat 107 of the funnel 106. The pitch of each of the helical guides 129 preferably diminishes progressively along its length downward from the mouth 130 until it approaches the horizontal at its lower end, thus providing a convergent helical channel through which the gaseous phase is caused to spin progressively faster as it approaches the throat 107.

Also coaxial with the conduit 101 and the funnels 106 and 128 and mounted outside of and just below each of the funnels 128 is a liquid tra 150, also in the shape of the frustum of a hollow inverted cone but open only at the top 151 (the base of the inverted cone) and closed at the bottom. The inner surface of each liquid trap 150 is secured to the outer surface of the funnel 128 immediately above it by one or more helical guides 149 to create one or more helical passages 152 between the funnel 128 and the liquid trap 150 through which the spin of the liquid phase accumulating in the liquid trap 150 can be augmented before it overflows the top 151 into the funnel 106 just below it.

In operation, the liquid phase is introduced continuously into the cap 116 through the liquid phase inlet 110 and the narrow slot 111 at a rate controlled by the liquid feed valve 113. Because of the tangential configuration of the liquid phase inlet 110 and the increase in the inlet velocity induced in the liquid phase by its convergence into the slot 111, the incoming liquid phase will be directed along the inside of the wall of the cap 116, against which it will spin around the longitudinal vertical axis of the conduit 101 fast enough to form a free vortex with a surface 140 approaching the vertical at the throat 107 of the highest of the funnels 106.

After enough of the liquid phase has been introduced into the cap 116 to narrow the inner diameter of the vortex surface 140 to that of the throat 107, the spinning liquid phase will overflow the edge of the throat 107 and spin radially outward and downward across the passage 143 between the outer surface of the funnel 106 and the inner surface of the highest of the funnels 128 in the form of a generally continuous annular liquid curtain 141 which screens the outlet of the passage 143.

The descending liquid phase continues to spin along the inner surface of the highest of the funnels 128 along which it continues its descent until it passes through the throat 131 and rises through the passage 152 between the outer surface of the funnel 128 and the inner surface of the liquid trap 150, from which it overflows the top 151 and continues its descent along the inner wall of the next highest funnel 106. The helical guide 149 helps to accelerate the spin of the liquid phase as it rises through the passage 152.

The spinning liquid phase continues downward to overflow the throats 107 of successively lower funnels 106, to form generally continuous annular liquid curtains 141 across the outlets of successively lower passages 143 to pass through successively lower throats 131 and passages 152 until it finally overflows the top 151 of the lowest of the liquid traps 150 into the sump 115 and is continuously discharged through the effluent liquid outlet 122 at a rate regulated by the effluent liquid valve 123.

Meanwhile the gaseous phase is introduced continuously through the gaseous phase inlet 124 into the lowest of the cylindrical members 102 at a rate controlled by the gaseous phase throttle valve 112.

Because of the tangential configuration of the gaseous phase inlet 124 and the increase in the inlet velocity induced in the gaseous phase by its convergence into the slot 127 the incoming gaseous phase will be spun around the vertical longitudinal axis of the conduit 101 in the same direction as the liquid phase.

The spin of the gaseous phase is further augmented as it passes through the lowest of the convergent helical passages 143 from the mouth 130 of the lowest of the funnels 128 to the generally continuous annular liquid curtain 141 emerging from the throat 107 of the lowest of the funnels 106. As the spinning liquid curtain screens the outlet of the passage 143, the spinning gaseous phase is obliged to bubble through it before it can enter the throat 107 and rise through the funnel 106 generally countercurrently to the falling liquid phase through which the gaseous phase must again bubble as it forms another annular liquid curtain screening the upward passage of the gaseous phase as it overflows the top 151 of the liquid trap 150 mounted below the next funnel 128 above the lowest.

The spinning gaseous phase continues its generally upward flow until it enters successively higher passages 143 screened by successively higher liquid curtains 141 through which it must bubble generally countercurrently until it ultimately reaches the effluent gas outlet 109 through which it is discharged from the apparatus at a rate controlled by the gaseous phase throttle valve 112.

The generally continuous countercurrent contact between the liquid and gaseous phases spinning in the same direction not only facilitates the transfer of heat, vapour, soluble substances and suspended matter from either phase to the other but it also tends to equalize the velocity of spin of the two phases. Thus, if an increase in the velocity of spin is required, it is sufficient to increase the spin of either phase, which will result in a faster spin for both.

This can readily be accomplished by the tangential introduction of vapour through one or more vapour inlets 137 mounted tangentially at convenient levels along the length of the conduit 101. The vapour can either be that of one of the constituents of the liquid phase or another condensible vapour or gas either soluble in the liquid phase or which will react in the apparatus to form one or more products which are so soluble.

If the apparatus is to serve to scrub particulate matter from the gaseous phase, the introduction of vapour through one or more vapour inlets 137 can also help to wet the suspended particles by supersaturating the gaseous phase with vapour which will condense upon them.

If the apparatus is to serve for continuous fractional distillation, the mixture to be distilled will be continuously introduced into one of the intermediate cylindrical members 102, preferably through a tangential inlet like the vapour inlet 137. The liquid phase inlet 110 and the gaseous phase inlet 124 will then no longer be required.

The mixture introduced through the inlet 137 (either in the vapour or liquid phase) will spin around the inner surface of the wall of the intermediate cylindrical member 102 until whatever portion remains in the liquid phase drains down the inner surface of the nearest funnel 106 immediately below it, forms a spinning annular liquid curtain 141 as it crosses the passage 143 from the throat 107 to the inner surface of the funnel 128 and follows the course previously described for the liquid phase until it descends into the sump 115 where its more volatile fraction is vapourized by the heating jacket 125 before its less volatile fraction is discharged through the effluent liquid outlet 122 at a rate controlled by the effluent liquid valve 123.

Meanwhile, the vapour portion of the mixture admitted into the intermediate cylindrical member 102 through the inlet 137 will rise to the mouth 130 of the nearest funnel 128 immediately above it, be spun faster and faster as it flows through the convergent helical passage 143 until it bubbles through the annular liquid curtain 141, spinning outward and downward across the passage 143 from the throat 107 of the funnel 106 next above it, and continues to follow the course previously described for the gaseous phase until it rises into the cap 116, where its less volatile fraction is condensed by the cooling jacket 126 before its more volatile fraction is exhausted through the effluent gas outlet 109 at a rate controlled by the gaseous phase throttle valve 112.

If the mixture to be distilled is complex, a number of units of this apparatus can be operated in series with one another. The vapour exhausted through the effluent gas outlet 109 of one unit can be introduced through the vapour inlet 137 of another unit while the liquid discharged through the effluent liquid outlet 122 of the same unit can be introduced into the inlet 137 of a third unit. This procedure can be continued through as many successive units of the apparatus as are necessary to separate the number of products ultimately required.

WHAT WE CLAIM IS: 1. A process for the continuous contact of a liquid phase with a gaseous phase and their subsequent separation from one another, the process comprising (a) introducing the liquid phase into a first conduit having a generally circular transverse section and a central longitudinal axis, the conduit being open at one end to provide an outlet for the liquid phase therefrom, the outlet being in the form of a central orifice with a circular rim in a plane generally perpendicular to the longitudinal axis of the conduit, (b) directing the liquid phase to flow through the first conduit generally toward and through the said central circular orifice, (c) spinning the liquid phase in the first conduit about the longitudinal axis thereof fast enough to form the liquid phase flowing through the central circular orifice into a generally continuous annular spinning liquid curtain connecting the first conduit with an overlapping coaxial second conduit, the second conduit also having a generally circular transverse section, thereby providing a generally annular space between the two interlapped conduits, (d) introducing the gaseous phase into the annular space between the two interlapped conduits, (e) directing the gaseous phase to flow through the said annular space in a path surrounding, but generally in the same axial direction as, the path of the liquid phase flowing through the first conduit, whereby the gaseous phase must pass through the generally continuous annular spinning liquid curtain connecting the two interlapped conduits in order to occupy an inner space surrounded by the annular spinning liquid curtain, (f) withdrawing the gaseous phase from the said inner space, and (g) separately withdrawing the liquid phase from the second conduit.

2. A process as claimed in claim 1, comprising spinning the gaseous phase in the same direction and about the same longitudinal axis as the annular spinning liquid curtain before the gaseous phase is passed through the annular spinning liquid curtain.

3. A process as claimed in claim 2, in which the velocity of spin of the gaseous phase is accelerated by the introduction thereinto of a vapour in a generally circumferential direction, at a higher circumferential velocity than that of the gaseous phase.

4. A process as claimed in any preceding claim, in which heat is transferred from either phase into the other phase.

5. A process as claimed in any preceding claim, in which at least one constituent of either phase reacts chemically with at least one constituent of the other phase.

6. A process as claimed in any preceding claim, in which at least one constituent of either phase is transferred physically from that phase to the other phase.

7. A process as claimed in claim 6, in which at least one constituent of the gaseous phase is the vapour of at least one constituent of the liquid phase.

8. A process as claim ed in any preceding claim, in which a suspension of eit er phase

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **.

If the apparatus is to serve for continuous fractional distillation, the mixture to be distilled will be continuously introduced into one of the intermediate cylindrical members 102, preferably through a tangential inlet like the vapour inlet 137. The liquid phase inlet 110 and the gaseous phase inlet 124 will then no longer be required.

The mixture introduced through the inlet 137 (either in the vapour or liquid phase) will spin around the inner surface of the wall of the intermediate cylindrical member 102 until whatever portion remains in the liquid phase drains down the inner surface of the nearest funnel 106 immediately below it, forms a spinning annular liquid curtain 141 as it crosses the passage 143 from the throat 107 to the inner surface of the funnel 128 and follows the course previously described for the liquid phase until it descends into the sump 115 where its more volatile fraction is vapourized by the heating jacket 125 before its less volatile fraction is discharged through the effluent liquid outlet 122 at a rate controlled by the effluent liquid valve 123.

Meanwhile, the vapour portion of the mixture admitted into the intermediate cylindrical member 102 through the inlet 137 will rise to the mouth 130 of the nearest funnel 128 immediately above it, be spun faster and faster as it flows through the convergent helical passage 143 until it bubbles through the annular liquid curtain 141, spinning outward and downward across the passage 143 from the throat 107 of the funnel 106 next above it, and continues to follow the course previously described for the gaseous phase until it rises into the cap 116, where its less volatile fraction is condensed by the cooling jacket

126 before its more volatile fraction is exhausted through the effluent gas outlet 109 at a rate controlled by the gaseous phase throttle valve 112.

If the mixture to be distilled is complex, a number of units of this apparatus can be operated in series with one another. The vapour exhausted through the effluent gas outlet 109 of one unit can be introduced through the vapour inlet 137 of another unit while the liquid discharged through the effluent liquid outlet 122 of the same unit can be introduced into the inlet 137 of a third unit. This procedure can be continued through as many successive units of the apparatus as are necessary to separate the number of products ultimately required.

WHAT WE CLAIM IS: 1. A process for the continuous contact of a liquid phase with a gaseous phase and their subsequent separation from one another, the process comprising (a) introducing the liquid phase into a first conduit having a generally circular transverse section and a central longitudinal axis, the conduit being open at one end to provide an outlet for the liquid phase therefrom, the outlet being in the form of a central orifice with a circular rim in a plane generally perpendicular to the longitudinal axis of the conduit, (b) directing the liquid phase to flow through the first conduit generally toward and through the said central circular orifice, (c) spinning the liquid phase in the first conduit about the longitudinal axis thereof fast enough to form the liquid phase flowing through the central circular orifice into a generally continuous annular spinning liquid curtain connecting the first conduit with an overlapping coaxial second conduit, the second conduit also having a generally circular transverse section, thereby providing a generally annular space between the two interlapped conduits, (d) introducing the gaseous phase into the annular space between the two interlapped conduits, (e) directing the gaseous phase to flow through the said annular space in a path surrounding, but generally in the same axial direction as, the path of the liquid phase flowing through the first conduit, whereby the gaseous phase must pass through the generally continuous annular spinning liquid curtain connecting the two interlapped conduits in order to occupy an inner space surrounded by the annular spinning liquid curtain, (f) withdrawing the gaseous phase from the said inner space, and (g) separately withdrawing the liquid phase from the second conduit.
2. A process as claimed in claim 1, comprising spinning the gaseous phase in the same direction and about the same longitudinal axis as the annular spinning liquid curtain before the gaseous phase is passed through the annular spinning liquid curtain.
3. A process as claimed in claim 2, in which the velocity of spin of the gaseous phase is accelerated by the introduction thereinto of a vapour in a generally circumferential direction, at a higher circumferential velocity than that of the gaseous phase.
4. A process as claimed in any preceding claim, in which heat is transferred from either phase into the other phase.
5. A process as claimed in any preceding claim, in which at least one constituent of either phase reacts chemically with at least one constituent of the other phase.
6. A process as claimed in any preceding claim, in which at least one constituent of either phase is transferred physically from that phase to the other phase.
7. A process as claimed in claim 6, in which at least one constituent of the gaseous phase is the vapour of at least one constituent of the liquid phase.
8. A process as claim ed in any preceding claim, in which a suspension of eit er phase

in the other is removed from suspension consequent to the passage of the gaseous phase through the generally continuous spinning liquid curtain.
9. A process as claimed in any preceding claim, in which particulate matter in suspension in the gaseous phase is transferred from the gaseous phase to the liquid phase.
10. A process as claimed in claim 9, in which at least part of the particulate matter is wet by a liquid before the particulate matter is transferred to the liquid phase.
11. A process as claimed in claim 10, in which the liquid is formed by the condensation of its vapour directly upon the surfaces of the particulate matter in suspension in the gaseous phase.
12. A process as claimed in any preceding claim, in which a wetting agent is carried by the liquid phase.
13. A process for the continuous contact of a liquid phase with a gaseous phase and their subsequent separation from one another, substantially as herein described with reference to the accompanying drawings.
14. An apparatus for the continuous contact of a liquid phase with a gaseous phase and their subsequent separation from one another, the apparatus comprising (a) a first conduit having a generally circular transverse section and a central longitudinal axis, the conduit being open at one end to provide an outlet for the liquid phase therefrom, the outlet being in the form of a central orifice with a circular rim in a plane generally perpendicular to the longitudinal axis of the conduit, (b) means for introducing the liquid phase into the first conduit and for directing the liquid phase to flow through the conduit generally toward and through the said central circular orifice, (c) a second conduit having a generally circular transverse section, the second conduit being coaxial with the first conduit and surrounding the central circular orifice, whereby the two conduits interlap to define an annular space therebetween, (d) means for spinning the liquid phase in the first conduit about the longitudinal axis thereof fast enough to form the liquid phase flowing through the central circular orifice into a generally continuous annular spinning liquid curtain connecting the first conduit with the second conduit, (e) means for introducing the gaseous phase into the annular space between the two interlapped conduits, (f) means for directing the gaseous phase to flow through the said annular space in a path surrounding, but generally in the same axial direction as, the path of the liquid phase flowing through the first conduit, whereby the gaseous phase must pass through the generally continuous annular spinning liquid curtain connecting the two interlapped conduits in order to occupy an inner space surrounded by the annular spinning liquid curtain, (g) an outlet for the gaseous phase from the said inner space, and (h) a separate outlet for the liquid phase from the second conduit.
15. An apparatus as claimed in claim 14, which comprises means for spinning the gaseous phase in the same direction as the liquid phase before the gaseous phase is passed through the annular spinning liquid curtain.
16. An apparatus as claimed in claim 14, which comprises a series of at least three conduits, each having a generally circular transverse section and a common central longitudinal axis and each conduit except the last in the series being open at the far end to provide an outlet for the liquid phase therefrom, the outlet being in the form of a central orifice with a circular rim in a plane generally perpendicular to the common longitudinal axis and surrounded by the next conduit in the series, whereby adjacent conduits interlap to define a series of coaxial annular spaces therebetween, thereby providing a series of generally parallel passages for the gaseous phase through a corresponding series of generally continuous annular spinning liquid curtains connecting the adjacent interlapped conduits.
17. An apparatus as claimed in claim 15 or claim 16 as dependent on claim 15, in which the means for spinning the gaseous phase comprises at least one stationary guide in the annular space between adjacent conduits capable of diverting the direction of flow of the gaseous phase there to accelerate its rate of spin around the longitudinal axis of the conduits.
18. An apparatus as claimed in claim 17, in which the guide comprises at least a part of a helix whose pitch diminishes progressively along its length to provide a convergent passage to accelerate the spin of the gaseous phase.
19. An apparatus as claimed in any one of claims 14 to 18, in which at least two units of the apparatus are mounted above one another in series.
20. An apparatus as claimed in claim 19, which comprises a liquid trap at the bottom of the lowest conduit of a higher unit, to provide an outlet for the liquid phase from the lower end of the conduit into the upper conduit of the next lower unit while denying passage in the opposite direction to the gaseous phase.
21. An apparatus as claimed in claim 20, in which at least one outlet for the liquid phase from the liquid trap is directed circumferentially about the longitudinal axis of the conduits.
22. An apparatus as claimed in any one of claims 14 to 21, in which at least one of the conduits is a funnel converging toward the outlet for the liquid phase therefrom.
23. An apparatus for the continuous contact of a liquid phase with a gaseous phase and their subsequent separation from one another, substantially as herein described with reference to the accompanying draw ings.

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