US2172222A - Centrifugal fluid-treating apparatus and seal - Google Patents

Description

Sept. 5, 1939.- w. J. PODBIELNIAK ,2 CENTRIFUGAL FLUID-TREATING APPARATUS AND SEAL Filed Aug. 5, 1937 2 Sheets-Sheet l 93 w. J. PODBIELNIAK 2,172,222

CENTRIFUGAL FLUID-TREATING APPARATUS MID SEAL Filed Aug. '5, i957 Patented eptr 5, 1939 PATENT OFFICE OENTRIFUGAL Film-TREATING 'TAPPARATUS AND SEAL w ne;- J. fodbieiniak, Chicago, 111., assignol' to BeniaminB. Schneider, Chicago, Ill.

Application August 5, i937, sci-m No. 157,516

" in Claims." '(01. 261-83) The present invention relates to improvements in the method and apparatus for effecting counter-current exchange between fluids, as between liquids and vapors or gases, or between liquids of different densities-that are more or less completely immiscible; and more particularly to sealing devices for use in connection therewith and with other devices having rotatable parts such as centrifugal fractionating apparatus, centrifugal pumps, turbines and like apparatus.

In my prior Patent No. 2,004,011 issued June4, 1935, and my prior applications Serial No; 5,059,

, flied February 5, 1935, and Serial No. 19,327, filed May 1, 1935, which applications have issued as Patent 2,093,645, dated Sept. 21, 1937, and Patent 2,044,996, dated June 23, 1936, respectively, and in my prior application to a Centrifugal treating apparatus Serial No. 87,224, flied June 25, 1936,

,I have described methods and apparatus for the .apparatus therein set forth, counter-current flow between a liquid condensate or reflux and alighter fluid or vapor is brought about by means of centrifugal force, the reflux or heavier liquid being caused to flow outwardly through a rotating spiral passageway of increasing radius, counvapor. Thus, a much greater efliciency in mmf tionation, absorption, chemical or contact action may be secured than in apparatus of the types hitherto known.

The presentinvention is a continuation-in- P rt of the invention described and claimed in my prior co-pending application to a Centrifugal fluid-treating apparatus and seal, Serial No. 87,223, filed June 25, 1936. It is related to my co-pending application, Serial No. 87,224, and may be readily adapted to treat air to condition it as. therein described and claimed.

In centrifugal counter-current treating apparatus of thetype hereinabove described and inlike apparatus, I have found-it advisable, and in larger apparatus, necessary to use a liquid seal to prevent leakage and bypass of the gases or- .vapors and of the reflux passing through the,

rotor, as the conventional packing constructions such as the stuffing box, spring-held packing rings, etc., leak too rapidly and are not practicable for large diameters, high rubbing velocities and vibrating joints and are not readily constructedto handle corrosive liquids, vapors or jgases.

In my prior application Serial No. 87,223, I described and claimed a liquid seal for centrifugal counter-current exchange and fractionatingrli apparatus, centrifugal pumps, turbines and the like which would operate effectively for liquids of a large range of densities, internal pressures, viscosities and surface tensions, such as water, salt water solutions and glycerine, aromatic hydrocarbons such as benzene, toluene, xylene and mixtures thereof, various petroleum fractions, pine oil, coal tars, coal tar acids, and the like. In the operation of such seals, I have found that under. some circumstances, suchfor example, as excessively high pressures or surges off the vapors undergoing fractionation or other treatment from. the kettle, some of the vapors may pass'directly into thezseal and contaminate the seal liquid and ultimately the treated vapors. To overcome this tendency I have provided a seal device which may be employed separately, or conjointly with the aforementioned seal to efiectively and substantially completely prevent the by-pass of kettle vapors through the seal regardless of the surging tendencies of the vapors issuing from the kettle and which treats or fractionatesany vapors which force their way therethrough, so that any condensate thereof which may form in theseal chamber will not contaminate the seal liquid."

. The seal devic se i fleet ff ter-current to an inwardly moving lighter fluid or e Wes n e as bu er and trio, angularly disposed. reentrant grooves and the otherwith a plurality of concentric-webs positioned in the grooves. The mutually coacting parts of the seal device form a restricted labyrinth path of great length through which the gases or vapors. must flrst find their way before they can enter the liquid seal chamber. 'In the movement of the gases through this path, condensation of portions thereof takes place and this condensate serves to cool and fractionate additional vapors tending to pass therethrough.

- The arrangement of the path'is such as o resist theflow of any vapors tending to pass therethrough and in consequence to cooperatewith 'of which is provided with a plurality of 'concenthe liquid seal to enable the latter to withstand high pressure drops across the seal.

This invention possesses manyother advantages which may be made more easily apparent from a consideration of an embodiment of the invention. For this purpose there'has been shown one form of the invention in the drawings accompanying and forming part of the present specification. This form shall now be described in detail to illustrate the general principle of the invention; but it is to be understood that the invention is'not limited to the details thereof, except as set forth in the appended claims.

' Referring to the drawings:

Figure 1 is a diagrammatic view, with parts in section and partly broken away, of apparatus suitable for carrying the invention into effect;

Fig. 2 is an enlarged fragmentary sectional view thereof showing the construction of both the centrifugal liquid and labyrinth seals;

Fig. 3 is an enlarged fragmentary sectional view of the elements comprising the labyrinth seal, showing these elements in position preparatory to assembling the seal; and.

Fig. 4 is a similar view showing the relationship of the elements in a subsequent stage of the assembly operation.

m the form of the invention shown in the drawings, a plurality of rotor sections III are provided in which the fluids to be treated are brought into contact by a counter-current movement set up by centrifugal force as described in my prior applications and patents. The rotor sections ID are rotatably mounted within a stationary housing II on a hollow hub 23 secured at its ends to horizontally disposed rotatable shafts I2. The power for rotating the shafts I2 and rotors is transmitted from some suitable source to the pulley I3 mounted on one of shafts I2, as by a motor and belt (not shown). The shafts I2 rotate in and are steadied by stationary radial bearings or the like positioned within combination stuffing and bearing boxes I4. The housing II is fluid-tight and is provided with an inlet I5 through which the light fluid'or vapor undergoing treatment enters.

The rotor sections lll within the housing II are each provided with a passageway II (see Fig. 2) of increasing radius which opens at its outer turn within the casing II. The passageway-may be a spiral or of other suitable form, for example, properly communicating concentric passageways. Each rotor section Ill, the-first being designated I, is in the form of a drum and is provided with circular end plates l8 and I9 between which the turns of the spirally wound sheets '20 are retained to form the spiral passageway H. The edges of the spirallywound sheets 20 are forced into spiral grooves in the opposed faces of the end plates I8 and I9 to form fluid-tight joints as shown inmy prior applications and the assemblies of therotors are retained in a unitary structure as by. the end pressure bolts 2.I

. A perforated shell 20' surrounds each rotor section'andis secured to the end plates l8 and IS in any desireed manner as by a weld. The perforations in shells 20' are of a size and numher to permit the ready ingress of theyapors from the casing II to. the spiral passageways. The innermost turn ofeach passageway I'I opens adjacent the cylindrical hub 23, which is provided within the .rotor sections with series of openings22 for the passage of fluids into and out of the rotor sections. The hub 23 extends beyond thecasing II through an opening in end plate II, into a chamber I6 provided with outlet I'B'. The portion of the hub 23 outside of the rotor section II) and intermediate this section and the. chamber I6 is imperforate and provides a passageway for the fluid passing from the rotor to the outlet I6 as well as for the reflux or heavier fluid passing into the rotors: It is now apparent that the vapors, gases or otherlight fluid will pass under a suitable pressure differential through the inlet I into the casing II and from it into the spiral passageway Il, transverse the latter and pass out through the openings 22 in hub 23, through the imperforate portion of hub 23 outside of the rotor section, through openings 22' in hub 23 and through the outlet I6. Fromthe outlet, the treated vapors or fluids ,may pass to a condenser or other receiving device.

Heavy-fluid supplied to the apparatus, for example, or condensate or reflux in a fractionation operation, or the absorption or counter-current exchange fluid is made use of in a sealing device to prevent the escape of vapors between the housing II and the outlet I8 and to prevent the vapors issuing from the apparatus without first being treated in the rotor sections. In fact, this sealing device may include a liquid centrifugal seal 25 of the vane andrecess type as described in my prior application Serial No. 87,223. In addition, I provide-a form of seal, which. for convenience may be called alabyrinth seal, desig-, nated as a whole' by the numeral 29, which is positioned within the housing II, suitably adjacent the centrifugal seal,'designated as a whole by the numeral 25, and inthe path of the vapors between the housing II and the seal 25. Seal 2l -serves to prevent direct communication between the gases or vapors in housing II and seal 25 or the exterior of the housing and is adapted to modify the character of gases or vapors passing therethrough for a purpose and in a manner to be hereinafter more fully described.

The seal 25 is of the type described in my prior application Serial No. 87,223 and is formed with an annular liquid seal chamber 26- between the casing' II and the exit chamber I6 and surrounding the imperforate portion 23' of hub 23. This chamber receives liquid, such as vapor condensate or other. suitable liquid, which in operation forms an annular body of sealing liquid, into which-extends an intermediate rotating vane 21 dividing theannular chamber. The vane 21 is secured to the imperforate portion 23 of hub 23 between the hub openings 22 and 22' and rotates there-j with. Ribs 28 may be suitably formed on one or both sides of the vane to aid in imparting motion to the seal liquid. The rotatable vane propels the liquid centrifugally to form an annular body in the seal chamber and the outer end of the vane extends into the body of seal liquid to keep it inrnotion during operation and prevents the by-pass of fluids passing through the apparatus.

The seal chamber 26 may be 'suitably'supported forms the peripheral wall. of the chamber, and an annular plate 3| is secured to ring 30 to form the other side of the chamber. A'collar 32 may be-secured as by a drive flt to hub 23 adjacent .to vane 21 for a purpose to be described. This collar extends into a recess in member 2 2 with a suilicient clearance to form a passageway to the seal chamber 26.

As set'forth in my prior application Serial No.

87,223 a liquid seal of the characterdescribed op erates effectively with proper clearances between the vane 21 and the opposed faces of theseal' chamber 26 and with various liqiiids. As

' drawings in which the inside diameter of the vane is in the order of four, inches, its outside diam eter in the order of nine inches andwitli' cleats or. ribs on the upper and lower side oith vane in the order of one-eighth of an inch in lieig hhthe seal will operate effectively at a clearance in the ditions. As the body of liquid on the inner side order of flve-eighths of an inchbetweenthe vane and the opposed faces of the seal chamber when the vane is rotated in the order of 1200 to 2000 n. P M. with any liquid likely'to'be distilled ii the chemical industry, including wateifgand not gasoline, and is ,capable'of resisting pressure drops of from ten inches to fifteen inches and more of mercury. Obviously, the abilityfloi the seal to resist pressure drops is dependent upon the specific gravity of the liquid used in theseal; the-greater the specific gravity of the liquid, the greater the centrifugal pressure at the eriphery of the seal and hence, the greater the pressure drop that can be resisted.

It is obviousthat these clearance limits as above set forth may be somewhat varied, depending upon the dimensions of the seaLtlie surfae' tem sion of the liquid used and the speed of the mov ing parts, without destroying the operativeness of the seal.

As the seal chamber 26 communicates with the interior of the casing there is a tendency for .the

vapors or gases in the latter to diffuse through the passageway entering the seal chamber and condense in the relatively cold liquid of the seal,

' thus contaminating the seal liquid, impairing the effectiveness of the seal, and ultimately contaminating the condensed fractions of .the distilled vapor. As set forth in my prior application Serial No. 87,223, above referred to, I have found that this can be effectively prevented either by continuously withdrawing a small amount of seal liquid under the full. pressure. of the periphery and flashing it at a point in the path of the vapors entering the seal; or preferably by continuously withdrawing a portion of the liquid from the seal,

the casing into the seal chamber. Clearances in the order of one-sixteenth of aninch and even less have been found quite eflective. As vapors of the seal liquid are thus used to counteract the diffusion of the kettle vapors, condensation of.

any part thereof within the seal will not contaminate'the seal liquid. The uncondensed portion may force its way into the stationary lionsmg ll through the labyrinth seal 24 and may be "returnedjto the kettle through a suitable trapped return pipe (not shown). In order to prevent the withdrawal of an unnecessary quantity of liquid from 'theseal chamber, the rate ofvflow can be determined by a flow-meter in the line stan controlled by a valve as shown and described in my prior application, Serial No. 8.'l,223.

In a fractional condensation process, the centiffugal seal operates under non-equilibrium coni the vane i1 is subjected to the pressure of the vapors in the kettle and the vapors from the the axis-of rotation of the rotor than the level 0f the liquid on the outer side of-the vane. In addition, the liquid on the inner side of the vane islheated by-both the. kettle vapors and the vapors from the vaporizer 34 whereas the liquid (in the p'uterside of the vane is positively-cooled with added reflux to overcome the effect of heat transfer through the rotating vane endotherwise, and to cool the body of liquid to improve its'sealing properties. To accomplish this, reflux,

liquid from the condenser iiows through a conduit' (not shown) and a regulated quantity thereto maintainthe desiredcooled relationship of the liquid on the outer side of the vane and .to main tain the liquid at the desired level. It is obvious that the liquid level on the inner side of the vane is'a function of the liquid level on the outer side of the vane and the pressure difference across the seal. This added condensate may serve to build j up the body of liquid in the sealchamber to an excessive level. If this takes place, the added built-up pressure of the liquid on the outer side of the vane urges some of the liquid through the reflux control pipe 39 against the pressure of the reflux entering thepipe until the desired ,level' of the liquid is restored. The desired liquid vaporizing it and continuously introducing the .level is thus automatically maintained at all vaporized liquid at a point inside the liquid level of the seal on the side toward thecasingfi,

As illustrated inthe drawings, the seal-liquid under the full pressure at the periphery maybe bled through conduit 33 and vaporized in a vaporizer or heater 34 which may be heated in'any convenient manner, as for instance laysteam, electricity or gas firing. The liquid is vaporized and the vapors conducted through return, conduit 35 and a radial passageway 36 in plate 29 and *enter the seal, is advantageously made quite small so that a minimum amount of vapor will serve to counteract effectively the diffusion of vapors from times during operation of the device. It is thus apparent that the desired non-equilibrium conditions. are continuously maintained throughout the operation of the device. v

In counter-current exchange operations such as fractionaldistillation, gas absorption heat exchange and the like, the centrifugal liquid seal 25 serves efliciently toprevent the by-pass of vapors or gases from the casing ii and thus prevents the contamination of the seal liquid and the ultimate contamination of the treated vapors or gases passing through-the outlet i6; I-tfmay be desirable, however, to provide an additional seal or partial. sealing means, referred to above as the labyrinth seal 24, within the casing and intermediate the liquid seal and the rotors; to assist liquid seal 25 to take care ofall or part of Lthefpressure drop between the interior of the rotors and the outlet-l6 and at the same time to impede the passage, by diffusion or otherwise,

35 ,of is introduced intothe upper part of the seal a of vapors tending to find their way therethrough. In this manner by-pass of the vapors from the casing, regardless of pressure is substantially entirely prevented and in instances where vapors find their way through the labyrinth seal and into the liquid seal, these vapors have been so treated in theirpassage through the labyrinth seal that they are substantially free from any undesirable constituents and hence condensation of these vapors in the seal liquid of the centrifugal seal will not contaminate the latter and neither will the vaporization of the seal liquid and the consequent intermingling of these vapors with the treated vapors passing through the outlet contaminate these treated 'vapors.

As stated above seal 2t is located within the housing 'II and comprisesa pair of opposed relatively movable members 40 and 0| (see Figs. 2, 3 and 4). Member 40 is in the form of an annular plate and is provided with inclined concentric grooves 62 in one face thereof. The

grooves 42 are inclined outwardly to form annular pockets in which liquid is held by centrifugal force during operation. Member M is likewise in the form of an annular plate and is provided with inclined projecting concentric webs 83 which extend into grooves 42 substantially equidistant from the sides thereof to form inclined concentric sealing passageways for a purpose to be described hereinafter.

Member in is rotatable by and with the rotor be readily apparent from consideration of Figs.

3 and 4. Member M is formed with the concentric webs A3 at a slightly lesser angle to the axis than in the desired final position. Member 6| with its projecting webs 03 is first positioned above the grooves 42 in member 00 as in Fig. .3 and the .webs are then inserted in the grooves 42 to permit telescoping of the parts, which is accomplished by'the application of substantial pressures. member MI and M, the edges of webs 43 contact the inclined inner walls of grooves 42 and upon the application of continued and sustained force, the webs 43 are forced outwardly and into the grooves and the parts are fully telescoped as shown in Fig. 4; After members 40 and 4| are in this position'they are axially separated until the webs 43 are positioned intermedalte and preferably substantially centrally of the grooves 42, as shown in Fig. 2.

In this manner I form a multiple labyrinth passageway 48 having a small clearance in the order of one-sixteenth of an inch or less. through which the kettle vapors must first pass before the vapors will condense and the condensate col-1 lects in pools at the bottoms of grooves 42 and is retained there by centrifugal force on rotation of plate All or pools of liquid may beprovided in In the first stage of the telescoping of .other counter-current exchange processes and In the operation of the apparatus in accord- 1 ance with my invention, as fully set forth in my prior applications above referred to, gases or vapors enter the housing and pass through the spiral passageways ll of the rotor sections. The

rotor and its associatedparts are rotated to de- 1 velop a centrifugal force which, dependent on radius and R. P. M., may be several hundred times the force of gravity but the tangential component of. which in the path of travel of the two fluids may be approximately equal to the force of 2 gravity or even less, although I prefer that it be substantially in excess of the force of gravity. In general, I have found it advisable to employ conditions of operation, rates of rotation and the like so that the tangential component of centrif- 2 ugal force effective-in the operation to force liquid outwardly through the passageway in the rotor is equivalent to three to five or more times the force of gravity. A speed of rotation of 500 to 2000 R. P. M. or higher in smaller devices has 3 been found suitable. The gases and vapors from the kettle are under pressure such that they pass inwardly through the .passageways l1, countercurrent to heavier fluid or reflux entering the hollow shaft 23, through the openings 22 and '3 pass out through opening 22' into chamber l6 and enter exit conduit IS. The vapors then pass to the condenser. Some of the vapors will, in a fractionation process, condense in passageways to form reflux liquid, or reflux or treating 4 liquid may be supplied to the rotors from the reflux condenser or other external source through the liquid supply conduits 49 (Fi 2) which extend through the stub shaft I2 adjacent the centrifugal seal. or treating liquid directly to a single rotor section I0 and thus insures an adequate and-uniform supply of liquid for each rotor section to effect the desired counter-current contact. It is of course to be understood that the number of liquid supply 5 conduits will vary, depending on the number of rotor sections mounted on hub 22 and their size.

The portion of reflux or treating liquid which is required to maintain the desiredseal level on the outer side of vane 21 is supplied through a 5 valved line (not shown) to conduit 39.

The reflux or treating liquid then flows directly into the. passageways Reflux or liquid entering and formed in the passageways l1 flows outwardly therethrough in a film or sheet against one wall of. the passageway, due to centrifugal force, counter-currently to the gases and vapors fiowing. inwardly therethrough. The relatively denser and heavier liquid therefore contacts and .scrubs relatively lighter gases and vapors, the

two streams of fluid being brought together intimately at their surfaces of contact by the centrifugal force applied. The liquid then discharges from the rotor sections In and collects in the bottom of housing II from which it drains back to the'kettle through a suitable trapped pipe (not shown).

While I have described the combined novel cen trifugal and labyrinth .seal as part of an apparatu's for'eflecting counter-current exchange be- 1 Each conduit 49 feeds reflux 4 prising a sealchamber into which any liquid likewould not be practical as in thehandling of hot corrosive fluids, in turbines and in like apparatus,

and under certain conditions the labyrinth seal may be used alone to prevent the by-pass of the kettle vapors or to efiect sealing. In centrifugal pumps, due to the absence of thermal efiects no special provisions are required, such as the vaporizer, to-prevent the leakage of gas through the seal liquid by diffusion, solution, etc. The same is true when the seal is used in an apparatus designed for oil absorption purposes.

While my description of a specific embodiment of the invention has included a centrifugal seal of the stationary recess type, it is obvious that the seal may be made of the rotating recess type in which the vane is stationary; This form of seal operates substantially the same as regards breakdown of the seal liquid due to pressure differences, velocity gradients etc. In the rotating recess type of ,seal the ribs or cleats may be formed on the. opposed facesof-the seal chamber in order to aid in keeping the seal liquid in motion during operation.- The stationary recess type of sealis more advantageous from the standpoint of assembly and disassembly and also because of the fact that a rotating vane is lighter and more easily balanced than a rotating recess.

I claim:

1. In combination with an apparatus for effecting counter-current exohange between fluids of different densities in' which the lighter fluid is caused to flow inwardly through a rotating rotor and counter-currently to a heavier fluid passing outwardly therethrough and in; which the rotor is positioned within a stationary housing filled with the lighter fluid, means forming a. centrifugal liquid seal'co'mprising a. seal chamber into which any liquid likely to be distilled is propelled by centrifugal force to form an annular body of seal liquid and a 'vane extending into the body of liquid. and means forming a passageway-between said seal chamber and the housing in which the lighter fluid in the housing tending to .fiow towardsthe seal chamber is caused to traverse-a tortuous path which resists suchflow.

2. In combination with an apparatus for effecting counter-current exchange between fluids of difl'erent densities in which the lighter fluid is caused to flow inwardly through a rotating rotor and counter-currently to a heavier fluid passing outwardly therethrough andin which the rotor is positioned within a stationary housing filled with the lighter fluid, means forming a centrifugal liquid seal comprising a seal chamber into which any liquid likely to be distilled is propelled by centrifugal force to form an annular body of seal liquid and'a 'vane extending into the body of liquid and means forming a passageway between said seal chamber and the housing in which the lighter fluid in the housing tending to flow towards the seal chamber is caused to traverse a tortuous path of decreasing radius which resists such flow.. i

3. In combination with-an apparatus foref fecting counter-current exchange between fluids of diiferent densities in which the lighterfluid is caused to flow inwardly through a rotating rotor and counter-'currentlyto a heavier fluid passing outwardly therethroug'h andin which the rotor is positioned within. a stationary housing filled with thelighter'fluid, means outside the housingforming a centrifugal liquid seal com in the housing to flow towards the seal 1y to be distilled is propelled by centrifugal force toiorm an annular body of seal liquid and a vane extending into the body of liquid and means forming a passageway between said seal chamber and the housing, a portion of said passageway will be forced to traverse a tortuous path of decreasing radius which resists such flow.

4. In combination with an apparatus for effecting counter-current exchange between fluids of different densities in which the lighter fluid is caused to flow-inwardly through a rotating rotor and counter-currently to a heavier fluid passing outwardly therethrough and in which the rotor is positioned within a stationary housing fllled with thelighter fluid, means outside the housing forming a centrifugal liquid seal comprising a seal chamber into which anyliquid likely to be distilled is propelled by centrifugal force to form an annular body of seal liquid and-a vane extending into the body of liquid and means forming a passageway between said seal chamber and the interiorpof the housing, the entrance to saidpassagewaybeing within the housing and being invthe form of a multiple labyrinth of decreasing radius whereby the tendency of the lighter fluid chamber is impeded; Y I

5. In combination with an apparatus for effecting counter-current exchange between fluids of different densities in which the lighter fluid is caused to flow inwardly through a rotating rotor and counter-currently to a-heavier fluid passing outwardly therethrough and in which.

the rotor is positioned within a stationary housm filled with the lighter fluid, 'means forming a centrifugal liquid seal comprising a seal chamber into which any liquid likely to be distilled is propelled by centrifugal force to form an annular body of seal liquid and a vane extending into the body of liquid, means forming a-multiple labyrinth passageway of decreasing radius in communication with the lighter fluid in the housing and means forming a passageway between said first named passageway and the seal chamber, said passageway having a relatively small cross-sectional area and said first named passageway being so constructed .and arranged as to impede the flow of lighter fluid tending to enter the seal chamber.

6. In combination with an apparatus f0 efiecting' counter-current exchange between fluids ofdifierent densities in which the lighter fluid is. caused to flow inwardly through a rotating rotor and counter-currently to a heavier fluid passing outwardly therethrough and in which the rotor is positioned within a stationary housing filled with the lighter fluid, means forming a centrifugal liquid seal comprising a seal chamber into which any liquid likely to be distilled is propelled by centrifugal force to form an annular. body of seal liquid and a vane extending into the body of liquid, means within the housing forming a labyrinth passageway comprising 'a plurality of coacting relatively movable members, said labyrinth passageway serving to impede the flow of fluid tending to flow therein and means forming a passageway between the labyrinth passag'eway and the seal chamber.

7. In combination with an apparatus for eflecting counter-current exchange between fluids of difl'erent densities in which the lighter fluid is' caused to flow inwardly through a rotating rotor and counter-currently to a heavier fluid passing outwardly therethrough and in which the rotor is positioned within a stationary housing filled with the lighter fluid, means forming a centrifugal liquid seal comprising a chamber into which any liquid likely to be distilled is propelled by centrifugal force to form an annular body of seal liquid and a vane extending into the body of liquid, means within the housing forming a labyrinth passageway comprisinga. plurality of coacting relatively movable members, one of said members being formed with concentric grooves and the other with projecting concentric webs positioned within and substantially centrally of the grooves and forming thereby the labyrinth passageway to impede the flow of any fluid tending to enter therein and means forming a passageway between the labyrinth passageway and the seal chamber.

8. In combination with an apparatus for effecting counter-current exchange between fluids of different densities in which the lighter fluid is caused to flow inwardly through a rotating rotor and counter-currently to a heavier fluid passing outwardly therethro ugh and in which the rotor is positioned within astationary housing filled with the lighter fluid, means for forming a centrifugal liquid seal comprising a seal chamber" into which any liquid likely to be distilled is propelled by centrifugal force to form an annular body of seal liquid and a vane extending into. the body of liquid, means within the housing forming a labyrinth passageway comprising a plurality of coacting relatively movable members, one of said members being formed with inclined concentric grooves which is secured to the rotor and adapted to rotate therewith and the other is stationary and is formed with inclined projecting concentric webs positioned within and substantially centrally of the grooves and means forming a passageway between the labyrinth passageway and the seal chamber.

9. In combination with an apparatus for eflecting counter-current exchange between fluids of different densities in which the lighter fluid is caused to flow inwardly through a rotating rotor and counter-currently to a heavier fluid passing outwardly therethrough and in which the rotor is positioned within a stationary housing filled with I the lighter fluid, means forming a centrifugal liquid seal comprlsinga seal chamber into which any liquid likely to be distilled is propelled by centrifugal force to form an annular body of seal liquid and a vane extending into the body of liquid, means within the housing forming a labyrinth passageway comprising a plurality of coacting relatively movable members, said labyrinth passageway serving to impede the flow of fluid tending to flow therein, means forming a passageway between the labyrinth passageway and the seal chamber, means for withdrawing liquid from the liquid seal chamber and means for vaporizing said liquid and introducing the vaporized liquid in the passageway between the labyringth passageway and the seal chamber.

10. In, combination with an apparatus for effecting counter-current exchange between fiuids'of different densities in which the lighter fluid is caused to flow inwardly through a rotating rotor and counter-currently to a heavier fluid passing outwardly therethrough and in which the rotor is positioned within a stationary housing filled with .the lighter fluid, means forming a centrifugal liquid seal comprising a seal chamber into "which any liquid likely to be distilled is propelled by centrifugal force to form an annular body of seal liquid and a vane extending into the body of liquid, means within the housing forming a labyrinth passageway comprising a plurality .ofcoacting relatively movable members, said labyrinth passageway serving to impede the flow of fluid tending toflow therein, one of said members being formed with inclined concentric grooves and the other with inclined projecting concentric webs positioned within and substantially centrally of the grooves, means forming a passageway between the labyrinth passageway and the seal chamber, means for withdrawing

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