US2897917A

US2897917A - Apparatus for separating moisture and condensable vapors from a gas

Info

Publication number: US2897917A
Application number: US696858A
Authority: US
Inventors: David U Hunter
Original assignee: Fairchild Engine and Airplane Corp
Current assignee: Fairchild Engine and Airplane Corp
Priority date: 1957-11-15
Filing date: 1957-11-15
Publication date: 1959-08-04
Anticipated expiration: 1976-08-04

Description

- Aug. 4, 1959 o. u. HUNTER 2,897,917

APPARATUS FOR SEPARATING MOIST AND NDE B 9 CO VAP FROM A INVENTOR DAVID U. HUNTER HIS ATTORNEYS APPARATUS FOR SEPARATING MOISTURE AND CONDENSABLE VAPORS FROM A GAS David U. Hunter, Huntington, N.Y., assignor to Fairchild Engine and Airplane Corporation, Bay Shore, N.Y., a corporation of Maryland Application November 15, 1957, Serial No. 696,858

Claims. (Cl. 183-77) This invention relates to apparatus for separating moisture and/or condensable vapors from a gaseous fluid.

The presence of moisture in a gaseous fluid used in a fluid system will often produce troublesome conditions. For example, in pneumatic brake systems, moistureladen air may cause failure of the brakes, expecially in cold weather when the moisture tends to freeze. In other types of systems embodying turbines and compressor units, moisture may cause erosion or rusting of the apparatus. For example, in centripetal turbines, it is not uncommon for moisture to become entrapped in the turbine wheel, and moisture so entrapped may cause erosion of the rotor, as well as damage to the nozzle.

The principal object of the present invention is to provide an apparatus for effectively separating moisture from a gaseous fluid.

Another object of the present invention is to provide an apparatus of this type wherein the gaseous fluid is discharged under controlled pressure and temperature conditions from the apparatus after the separation of mois ture therefrom.

These and other objects are achieved in the apparatus of the present invention. In this apparatus, a rotor of special design is adapted to be driven by the gaseous fluid from which it is desired to remove the moisture. The gaseous fluid under pressure is directed by one or more nozzles against the rotor to drive it at high speed. The impelling fluid then passes through one or more passages formed through the rotor, in which the moisture is separated from the gaseous impelling fluid and the gaseous fluid is discharged from the opposite end of the passage relatively free of moisture. Throughout the moisture separating length of the passage, the distance between the axis of rotation of the rotor and the surface of the passage remote irom the axis of rotation of the rotor progressively decreases. Thus any moisture particles contained in the gaseous fluid, by virtue of the fact that these particles are heavier than the gaseous fluid, tend to move under .the influence of centrifugal force toward the surface of the passage remote from the axis of rotation, and due to the high speed of rotation of the rotor, these particles are forced by the centrifugal force in an upstream direction toward the inlet end of the passage. At the inlet end of the passage, the moisture particles are discharged outwardly of the rotor by centrifugal force. This is possible due to the fact that the nozzle or nozzles which direct the impelling fluid against the rotor are offset laterally from the outward path of travel which the moisture particles follow as they are discharged from the inlet end of the passage through the rotor. The moisture thus discharged outwardly by centrifugal force is collected in an annular trough which surrounds the gap between the nozzle and the rotor, and the moisture flows by gravity toward a drain in the lower portion of the trough.

It is evident that the apparatus \of the present invention has several important applications. One of these ited States Pate applications is to turbines, especially turbines of the centripetal type, to prevent moisture from becoming entrapped in the turbine wheel. The invention is also readily adapted for use as an or gas drier.

For a complete understanding of the invention, reference may be made to the detailed description which follows and to the accompanying drawing in which the figure represents apparatus embodying the invention shown in a cross-sectional elevation view.

Referring to the drawing, a rotor, generally designated ill, is supported for rotation within a housing 11 by a pair of stub shafts l2 and 13 which are enclosed within the

hub portions

14 and 15, respectively, of the housing.

Hollow hubs

16 and 17 are formed integrally with the rotor at opposite ends thereof, and the hubs rotate on the stub shafts l2 and 13.

The rotor 19 comprises generally an inlet or upstream end .18, an outlet or downstream end 19, and an intermediate portion 20. The

ends

18 and 19 of the rotor are of larger diameter than the intermediate portion 28 thereof. Ample clearance is provided between the outer periphery of the rotor and the housing throughout its entire length. To prevent a flow of fluid through this gap, a labyrinth seal 21 is formed between the outer periphery of the rotor and the housing.

The rotor 10 is formed with an annular passage 23 therethrough which extends from the inlet 24 of the passage to the outlet 25 thereof. The passage 23 is coaxial with'the rotor. The inlet end 24 of the passage 23 is an annular opening formed in one end of the rotor 10. The opening 24, in other words, is disposed generally axially to the axis of rotation of the rotor. Downstream of the inlet 24, the passage turns inwardly in a gentle curve toward the axis of rotation of the rotor. Further downstream the passage turns in a generally axial direction, and the passage 23 continues in a more or less axial direction through the intermediate portion 20 of the rotor. However, at the discharge end 19 of the turbine wheel, the passage turns outwardly in substantially a radial direction to discharge the fluid outwardly through the passage 26 which communicates with the volute discharge duct 27 from which the fluid is discharged through .a discharge opening 28. Stationary vanes 34 in the passage 26 direct the discharged fluid in the desired path of flow into the duct 27.

The passage 23 contains a plurality of impeller blades 30 which extend the entire length of the annular passage 23, thereby subdividing the annular passages into a plu rality of separate passages. Also, the upstream end of the passage 23 contains a plurality of shorter impeller blades 30a which terminate in the upstream end 18 of the rotor and subdivide the passages defined by the blades 30. The blades 3t? and 3% are arranged alternately around the annular upstream end of the passage 23, and their upstream terminal edges are substantially flush with the end surface of the rotor. The effective cross-sectional area of the passage 23 gradually expands from the inlet 24 to a point downstream of the downstream ends of the blades 3%, permitting reduction in the temperature and pressure of the impelling fluid in this portion of the passage. In the intermediate portion 20 of the rotor, the surface a forming the outer periphery of the passage 23 (that is to say, the surface of the passage remote from the axis of rotation of the rotor) tapers slightly inwardly (that is, toward the axis of rotation of the rotor) in a downstream direction. Thus, it is apparent that the distance between the axis of the rotor and the outer surface of the passage 23 continues to decrease from the inlet 24 to the downstream end of the intermediate portion 20 of the rotor. As will be explained in more detail below, this surface permits moisture droplets or particles which form 3 on the surface a to be moved in an upstream direction toward the inlet 24 by the action of the centrifugal force.

The impelling fluid which drives the rotor is admitted into the housing through a passage 32, and then through one or more nozzles '33 which direct the impelling fluid through the inlet opening 24 of the passage 23 against one side of the

blades

30 and 30a, thereby imparting rtation to the rotor. The nozzle 33 is laterally olfset with respect to the inlet 24 of the passage 23, thus forming a gap 35 therebetween. In addition, the path in which the nozzle directs the fluid toward the opening 24 is either almost parallel with the axis of the rotor, or, as shown, it forms an acute angle therewith so as not to interfere with the moisture discharged through the opening 24 by centrifugal force. An annular trough 36 surrounds the outer end of the gap 35, and any moisture collected in the trough flows by gravity to the bottom thereof and is ultimately expelled from the housing through a drain 37.

Moisture particles are separated from the impelling fluid in the portions 18 and of the rotor. In these portions of the rotor, moisture particles, being heavier than the impelling gaseous fluid, are urged outwardly by the action of centrifugal force against the outer surface a of the passage 23, and due to the high speed of rotation of the turbine, the moisture is forced upstream along the surface a toward the inlet opening 24 and eventually into the gap between the laterally offset impeller nozzle and rotor inlet toward the trough 36 which surrounds the gap. The laterally offset position of the turbine nozzle allows the moisture to follow this path of flow without interference from the nozzle or the jet which is directed by the nozzle against the rotor. Because the moisture particles are hurled into the gap 35 from the opening 24 with both radial and tangential components of force, the moisture tends to flow through the trough to the lower portion thereof, from which it is carried off from the housing through the drain 37.

As thus far described, the invention is applicable for use as a moisture separating apparatus, as a drier, or as a turbine. In all of these applications, it is possible to discharge the impelling fluid through the discharge opening 25 of the passage 23 by the combined effects of centrifugal force and the upstream pressure of the fluid. In the form in which the apparatus is illustrated in the drawing, however, it is desired to discharge the fluid at a controlled elevated pressure and temperature, preferably as close as possible to the pressure and temperature of the fluid before it is introduced into the apparatus for the separation of moisture therefrom. Inasmuch as the fluid undergoes expansion in passing through the moisture separating

portions

18 and 20 of the rotor, the pressure and temperature of the fluid are substantially reduced. However, by designing the passage 23 so that the effective cross-sectional area thereof continues to de-- crease through the portion 19 of the rotor, the fluid may be discharged at an elevated controlled pressure and temperature. In fact, by proper design, the temperature may be controlled to approximate the temperature of the fluid upstream of the apparatus.

Although it is not important to the invention, the

stub shafts

12 and 13 are shown as being retained within the hollow hubs of the housing by resilient end seals 12a and 13w respectively. Obviously, however, if the apparatus were to be used as a turbine drive unit, a power take-off shaft would be connected with one of the ends of the rotor. Also, as shown, the housing is provided with an annular cavity 40 which surrounds the rotor, and in certain applications it may be desired to circulate a fluid through this passage to provide the desired temperature control of the rotor or the fluid passing therethrough. V 7

By way of summary, the impelling fluid is accelerated in passing through the nozzles 33, thereby increasing the velocity of the fluid and reducing the temperature and pressure thereof. Any moisture present or any Vapor which is condensed during this process will enter the rotor in a more or less axial direction. The speed of the rotor is such that the normal velocity of the impelling fluid relative to the rotor is moderate. The fact that the moisture particles may have a different velocity than the impelling fluid is not of very great importance inasmuch as the hard surface of the

blades

30, 30a will resist the impact of these moisture particles. As the moisture particles pass through the annular passage 23 between the blades 30, the moisture particles will be thrown to the outer surface a whereupon they will be moved in a direction opposite to the direction of flow of the impelling fluid, ultimately being expelled through the space intermediate the nozzle 33 and the rotor into the trough 36. As the impelling fluid progresses through the rotor, the temperature and pressure of the im elling fluid continues to fall, although the pressure and temperature of the impelling fluid are increased to the desired level on the compressor end 19 of the rotor before the fluid is expelled from the rotor into the discharge duct 27.

The compressor is so designed that virtually all of the turbine energy (allowing, of course, for turbine and compressor inefliciency) is restored to the fluid, raising the pressure as near to the inlet pressure as is practicable. At the discharge end of the compressor, the relative humidity of the impelling fluid is much less than It should be noted that in a moisture separator 100% relative humidity in the exit system is the best attainable. By suitable design of the compressor and turbine, the degree of moisture remaining in the exit system can be held to a very low amount. With water vapor in the air, it would be possible to reach a 32 dew point, and it is theoretically possible to obtain an even lower figure. In this case, ice tends to form in the gaseous stream. Any ice formed, however, is carried to the outer surface of the annular passage 23, and the heat conductivity through the rotor provides the necessary heat to melt the ice, allowing the liquid phase of the stream to be separated in the manner described above.

By suitable design, the liquid and solid particles which are directed by the nozzle or nozzles 33 against the impeller blades will be thrown back into the gap between the rotor and the nozzle and not back into the nozzle stream. A conventional centripetal turbine is subject to a much greater damage by foreign particles, because in such turbines the particles can bounce back and forth many times until they are reduced to very small size, before ultimately being carried by the impelling fluid through the rotor. This repetitive impact is the cause of undue wear on the rotor and blades. In the present invention, wear due to this cause is reduced to a fraction of what it would be in a conventional centripetal turbine.

Throughout the application, reference is made to the expulsion of moisture particles by the apparatus. It is understood, of course, that this also is intended to include the condensate of condensable vapors which are likewise expelled from the impelling fluid.

The invention has been shown and described by way of example only, and obviously many variations and modifications may be made therein without departing from the spirit of the invention. The invention, therefore, is not to be limited to any specified form or embodiment, except in so far as such limitations are set forth in the appended claims.

I claim:

1. Apparatus wherein moisture is separated from a gaseous fluid comprising a rotor, means supporting said rotor for rotation, a moisture separating passage in the rotor, inlet and discharge openings to and from said passage, said passage including a moisture separating upstream portion wherein the distance between the axis of rotation of the rotor and the surface of the passage remote from the axis of rotation of the rotor continues to decrease from the inlet opening throughout the moisture separating portion of the passage, whereby moisture carried by the gaseous fluid passing through the passage is moved by centrifugal force toward the surface of the passage remote from the axis of rotation and then along said surface toward the inlet opening, and means laterally offset from the inlet end of the passage for directing the fluid against the rotor for imparting rotation thereto, said laterally offset means preventing interference with the moisture discharged by centrifugal force from the upstream end of the rotor passage.

2. Apparatus as set forth in claim 1 wherein said rotor passage is an annular passage extending substantially coaxially with the axis of rotation of the rotor.

3. Apparatus as set forth in claim 2 including a plurality of impeller blades mounted at the upstream end of said annular passage.

4. Apparatus as set forth in claim 1 wherein the gaseous fluid is directed against the rotor for driving it by a laterally olfset nozzle, and wherein the inlet opening of the rotor passage is formed in a side wall of the rotor, thereby forming a gap between the nozzle and the inlet opening through which the moisture discharged through the inlet opening is free to pass outwardly.

5. Apparatus as set forth in claim 4 including an annular moisture collecting trough surrounding said gap.

6. Apparatus as set forth in claim 1 wherein the downstream end of said passage turns outwardly, whereby the gaseous fluid is discharged through said outlet opening at least in part by the action of centrifugal force.

7. Apparatus as set forth in claim 1 wherein the effective cross-sectional area of the passage increases from the inletopening to an intermediate portion of the rotor passage to permit expansion of the gaseous fluid, and wherein the effective crosssectional area of the passage decreases downstream of said intermediate portion, whereby the pressure and temperature of said gaseous fluid decreases in passing from the inlet opening to the intermediate portion of the passage, and increase before the gaseous fluid is expelled through said discharge passage.

8. Apparatus wherein moisture is separated from a gaseous fluid under pressure comprising a rotor, a passage formed in the rotor extending generally longitudinally thereof, impeller blades carried by the rotor at the upstream end of the passage, means for directing the fluid under pressure against said impeller blades to impart rotation to the rotor, said means being laterally offset and spatially separated from the inlet end of said passage to form a gap therebetween, the upstream end of said passage extending inwardly in a downstream direction, whereby moisture particles in the impelling fluid are urged by the centrifugal force of rotation in an upstream direction and are expelled from the inlet end of 6 said passage into the gap between the inlet end of the passage and the laterally oflset means for directing the impelling fluid toward the inlet end of the passage.

9. Apparatus wherein moisture is separated from a gaseous impelling fluid comprising a rotor, means supporting said rotor for rotation, impeller blades carried by said rotor, means defining a passage for conducting the fluid past said impeller blades, said passage extending inwardly so that moisture carried by the impelling fluid moves outwardly against the surface of said passage remote from the axis of rotation of the rotor and in an upstream direction past said impeller blades, means laterally offset from the upstream end of the impeller blades for directing the gaseous fluid against the impeller blades for imparting rotation to the rotor, whereby moisture is released from the upstream end of said rotor by centrifugal force, and moisture collecting means surrounding the upstream end of the rotor for collecting the moisture.

10. Apparatus wherein moisture is separated from a gaseous fluid comprising a rotor, means supporting said rotor for rotation, an annular passage in said rotor extending coaxially with the axis of rotation of the rotor, inlet and discharge openings to and from said passage, the upstream end of the passage extending inwardly toward the axis of rotation, the discharge end of said passage extending outwardly away from the axis of rotation of the rotor, and an intermediate portion thereof extending generally axially, the upstream and intermediate portions of said rotor passage constituting a moisture separating portion wherein the distance between the axis of rotation of the rotor and the surface of the passage remote from the axis of rotation of the rotor continues to decrease throughout from the inlet opening, whereby moisture carried by the gaseous fluid passing through the passage is moved by centrifugal force toward the surface of the passage remote from the axis of rotation and then along said passage toward the inlet opening, a nozzle laterally offset from said surface at the inlet opening so as not to interfere with the outward movement of said moisture, said laterally offset means directing a stream of the gaseous fluid from which the moisture is to be removed toward the inlet opening of said passage, and an annular trough surrounding the upstream end of said rotor for collecting the moisture thrown outwardly from the rotor by centrifugal force.

References Cited in the file of this patent UNITED STATES PATENTS 2,471,109 Hunt May 24, 1949 FOREIGN PATENTS 731,464 France May 30, 1932 700,100 Germany Dec. 13, 1940