US2575568A

US2575568A - Centrifugal gas-liquid separator

Info

Publication number: US2575568A
Application number: US709129A
Authority: US
Inventors: Jr Edward Topanelian
Original assignee: Gulf Research and Development Co
Current assignee: Gulf Research and Development Co
Priority date: 1946-11-12
Filing date: 1946-11-12
Publication date: 1951-11-20
Anticipated expiration: 1968-11-20

Description

Nov. 20, 1951 TQPANEUAN; JR 2,575,568

I CENTRIFUGAL GAS-LIQUID S EPARATQR Filed NOV. 12, 19516 3 Sheets-Sheet 1 MI-XTUR 011-1 OUTLE g vwvwfw DWBRD 'IOPANELIANJR Nov. 20, 1951 E. TOPANELIAN, JR 2,575,563

CENTRIFUGAL GAS-LIQUID SEPARATOR Filed Nov. 12, 1946 3 Sheets-Sheet 2 011. mscHfiR J AIR on 11 221 EDWA D TCPANEJJIANJR.

Nov. 20, 1951 E. TOPANELIAN, JR ,5

CENTRIFUGAL GAS-LIQUID SEPARATOR Filed'Nov. 12, 1946 I s-sneet's-sheet s IIHHIHHIN grwc/wtm EDWARD TOPfijNIILIf-XN, JR.

Patented Nov. 20, 1951 GENTRIFUGAL GAS-LIQUID SEPABATOB Edward Topanelian, Jr., Pittsburgh, Pa., assignmto Gulf Research & Development Company,

Pittsburgh, Pin, a corporation of Delaware Application November 12, 1946, Serial No. 709,129

1 Claim. 1

This invention relates to centrifugal gasliquid separators of the axial discharge type, and more particularly to a deaerator of this type especially, although not necessarily, for deaerating the oil in the lubrication systems of aircraft engines, in which the air or gas as it is centrifugally separated from the liquid is axially discharged through the rotor shaft.

The primary object of the invention is to provide a centrifugal gas-liquid separator of greater separating capacity and eflloiency than other devices of this class. A further object is to obtain or incorporate in the deaerating device an integral pumping action of high fluid efliciency. This is accomplished by certain improvements in an axial discharge type of centrifugal pump, not originally capable of deaerating a liquid and not previously used for that purpose, such as disclosed in Patent No. 2,233,825 granted March 4, 1941, to Walsh et al. for Pumps, without increased relative size and bulk, by employing an impeller having a hollow conical hub whose sides are provided with air holes located behind the longitudinally extending impeller blades and a hollow impeller shaft whose interior is in communication with the interior of the hub and hence with the air holes and with the air discharge duct in the casing, in such a way that the air, which remains around the hub and which accumulates behind the impeller blades as the oil or other liquid moves centrlfugally outwardly away from the hub as'the impeller is rotated, has a substantially liquid-free and unobstructed path of escape, offering minimum resistance to its discharge to the air outlet, by way of the interiors of the hollow impeller hub .and hollow impeller shaft.

Another important object of this invention is to provide a centrifugal deaerator of the above described character whose deaerating efficiency and capacity can be varied by changing the size, the number and the location along the axis of the hub of the air holes, which are formed through the wall of the hollow conical impeller hub, a single circumferential row of air holes located immediately behind the impeller blades near the base end of the conical hub providing effective deaeration, but of less volumetric capacity than is provided by additional rows of air holes arranged along the impeller hub from the base end of the hub toward the apex end thereof.

These and other objects of this invention are achieved by the provision of a casing and an axially rotatable impeller in the form of a generally 2 conical hub with blades joined thereto substantially parallel to its axis. The blades increase in height toward the apex of the hub, and advantageously extend from the base end of the hub to points near its apex. The portion of the generally cylindrical casing or housing which surrounds the impeller is tapered to closely fit the impeller throughout its length, and has a liquid discharge cavity, advantageously in the form of a substantially semiannular trough, located adjacent to the base end of the impeller for approximately axial discharge of the liquid and having a radial discharge at one end. Liquids are admitted to the casing at the smaller end of the impeller. Spaced substantially concentrically within the semiannular trough is a confined space comprising an annular air or gas discharge cavity having a tangential discharge passage communicating with the air outlet. The air or gas discharge cavity is in communication with perforations in the impeller shaft, which is hollow to provide an air discharge duct, and communicates with the interior of the conical impeller hub whose walls are formed with perforations opening therethrough immediately behind the impeller blades. As a result, the air or gas which is entrained in the liquid entering the casing during operation of the impeller and which becomes centrifugally separated from the liquid and accumulates behind the impeller blades as the liquid is thrown centrifugally outwardly, can discharge directly and immediately to the air outlet of the casing.

The accompanying drawings show a specific and presently preferred embodiment of the invention, but it will be understood that changes can be made in the construction and relative arrangement of the component parts, within the purview of the invention.

In the drawings:

Figure 1 is a central vertical section with some parts shown in elevation.

Figure 2 is a transverse vertical section taken on the line 2--2 of Figure 1.

Figure 3 is a transverse vertical section taken on the line 3-3 of Figure 1.

Figure 4 is an end elevation of the impeller. and,

Figure 5 is an elevation of the cup-shaped closure for one end of the casing, the outer surface of which is helically reduced to define the liquid discharge trough.

Referring to the drawings, the deaerator comprises a base 6 on which is mounted a generally cylindrical casing formed in three parts, an inlet portion or suction snout I, a central cylindrical member land a cup-shaped member II, the main body portion of which extends within the central member. While the central member 8 is approximately plain cylindrical, the suction snout I includes an annular flange 9 at its inner end, and an intermediate outwardly tapering or frustoconical part I, terminating in an internally threaded neck II, to which is adapted to be connected the pipe (not shown) which conducts the air and oil mixture .to the deaerator.

The suction snout I is assembled with the central cylindrical member 8 by means of circumferentially spaced bolts l2, passing through the flange 9 and the wall of the central member, and through the flange I3 on the outer end of the cup-shaped member [4, whereby the helix on its outer surface is assembled in position within the central cylindrical member 8.

The cup-shaped member l4 comprises the plain cylindrical part l5 which fits tightly in and reaches to the inner end of the central member 8. As shown in Figures 2 and 5, the plain cylindrical part [5 is helically reduced to define a spirally tapered liquid discharge trough I5 running circumferentially inside: the central cylindrical member 8, and graduated in axial depth from a maximum at the point l'l, coinciding with the inner end of the radial oil discharge pipe 18 entering the trough I6 through the wall of the central member 8, to a minimum at the point (8, the open side of the trough l6 facing and being open to the larger inner end of the suction snout I.

The inner surface of the projecting body of the cup-shaped member 14 defines a cavity whose largest diameter portion intermediate its ends constitutes the air discharge trough 20. An oil seal 2| is arranged in the inward end of the cavity, and between the seal 2| and the trough is disposed an antifriction shaft bearing 22. A similar shaft bearing 23 is disposed in the cavity at the outer end of the trough 20, the outer end of the cavity being closed by a gland 24 secured by studs to the helix, I4 and containing two axially spaced

oil seals

25 and 26, with a drain tube 21 leading from the space between these seals.

The impeller shaft, which is generally designated 28, extends through the mentioned oil seals and is rotatably mounted in the bearings 22 and to support the impeller 29 within the suction snout l.

The impeller shaft 28 comprises a solid portion extending outwardly from the gland 24 and adapted to be connected to a suitable driving means (not shown) for rotating the shaft at a suitable speed, such as 1750 R. P. M. for a sixinch impeller, and a tubular or hollow portion 3| which extends through the member l4 and into the impeller 29. The hollow portion 3| includes an externally enlarged part 32 which is located in the air discharge trough 20 and is confined between the bearings 22 and 23. The part 32 is perforated by a plurality of circumferentially spaced longitudinal rows of air holes 33, which establish communication between the bore of the shaft portion 32 and the air discharge trough 20. In this case, eight such rows of holes are shown, consisting of four holes each, but a greater or less number of rows and holes may be employed according to requirements, and in accordance with the number of rows and holes present in the impeller and in the perforated end of the hollow shaft portion 3 I It will be seen that the radial holes between hollow shaft portion 3| and air discharge trough 20 subject the air or gas passing therethrough to a centrifugal action and thus constitute a miniature blower assisting in the eduction process and a feature of this invention. Obviously, this centrifugal blower action may be augmented if desired by increasing the outer diameter of the shaft or by affixing radial blades between the rows of holes.

The impeller 25 has a hub portion 34 of approximately conical or bullet form as shown, the walls of the cone rounding oil at 35 into a substantially cylindrical portion 36. A conical nut 31 threaded or pinned on a stud 38 fixed in the end of the hollow shaft portion 3| secures the impeller to the shaft and forms the apex of the impeller, which is positioned in the region of the outer or smaller end of the tapered part In of the suction snout l.

The impeller has a plurality of blades 39, here shown as eight in number, which are advantageously integral with the hub 34. Each blade extends from the base end 40 of the hub to a point near the apex of the hub, as shown. Each blade terminates at the base end 40 of the hub in a flat radial portion 4-1, having substantially parallel edges which are parallel to the hub axis, and the outer edge 42 of each blade slopes away from the sides of the hub at the same angle as the wall of the tapering portion [0, so that the radial extension of the blades is greatest at their ends adjacent to the apex of the hub and the edges conform to and are closely spaced from the tapering wall of the portion ID of the suction snout I. As shown in Figure 4 of the drawings, the wider ends of the blades 39 are curvedly deflected in the direction of rotation of the impeller to provide the desired propeller action upon the oil to produce axial discharge thereof, toward and into the helical discharge trough [6. This is an important feature of this device which provides eiiicient pumping or propelling action on the\fiuid, accomplishing same with lower expenditure of driving power than other existing devices of this type, due to the tangential entry of the blade into fluid.

The inner end of the suction snout 1 has a relatively narrow plain annular recess 43 in which the blade portions 4! work and which extends entirely around the casing and with the annular portion 36 of the impeller forms a fluid discharge passage 44 which opens into the liquid discharge trough 16 throughout the circular length of the discharge trough. As shown in Figure l of the drawings, this discharge passage 44 is substantially narrower than the trough l6 and it opens only into a correspondingly narrow peripheral portion of the oil discharge trough [6, the remainder of the width of the discharge trough being occluded by the plain annular larger end portion 36 of the impeller hub 34.

The impeller hub 34 is hollow and has an axial tubular part 45 which receives the hollow portion 3| of the impeller shaft. In the case of an impeller having eight blades 39, as herein shown, the hollow shaft portion 3| and the tubular hub portion 45 may have eight cireumferentially spaced rows of registered air holes 46 and 41, respectively, each row having five holes, whereby communication between the interior of the hub and the interior of the shaft portion 3! is established.

The walls of the impeller hub 34 are pierced by holes 48 located just outwardly of the basal air outlet pipe 49.

portion 35 of the hub, and immediately behind each blade 39, as indicated in Figure 4, this being the region of the surface of the hub 34 and blades 39 whereat the densest masses of air separated from the air and oil mixture as it is acted upon by the impeller 29 collect as the oil, due to its greater density moves centrifugally outwardly as the impeller turns. The pressures exterted upon these masses of air by the action of the impeller blades and by the action of the oil as it is operated upon by the impeller, cause these masses of air to escape through the air holes 48 into the interior of the hub 34 and thence through the holes 46 and 47 into the interior of the shaft portion 3|, and into the air discharge trough 20 through the shaft holes 33, finally passing from the trough 20 through the tangentially arranged air outlet passage 48 to which is connected an The horizontal air outlet pipe 49 leads from thgjottom of the air discharge trough 20, as shown in Figure 2, and includes at its outer end an upwardly directed air outlet 50 and a downwardly directed oil drain 5|, which gravitationally drains any oil present.

As shown in Figure 1, instead of one air hole 48 behind each impeller blade 39, there may be additional holes 52 formed throughthe basal hub portion 36, and further holes 53 formed through the hub wall along the rear sides of the blades 39 to increase the air stripping capacity of the deaerator.

In tests made with the herein described deaerator installed in the line connecting the discharge of the scavenge pump with the inlet to the hopper of an aircraft lubrication system, specifically that of a B-17 Army bomber, a back pressure of 20 p. s. i. was applied to the deaerator to represent the pressure which would be applied by the cooler normally installed in the scavenge pump discharge line, and a very marked reduction to about 5 per cent air entrainment in the oil supply tank outlet oil to the pressure pump with the deaerator in operation was noted, compared to about 18 per cent of air entrained in the oil at the same point in the lubrication system without the deaerator in operation.

What I claim as my invention is:

A centrifugal deaerator comprising a casing formed by a central cylindrical member, a radially flanged cup-shaped member closely fitted within and closing one end of said cylindrical member, and a frusto-conical inlet snout member affixed to the other end of said cylindrical member, the outer surface of said cup-shaped member being formed with a helically reduced portion which defines with the inner wall of said cylindrical member a semi-annular passageway of increasing depth in axial direction and open to the admission of fluid from said snout member, a discharge outlet for liquid communicating with said semi-annular passageway in the region of its greatest depth, a rotatable shaft extending axially through said cup-shaped member and supported therein in spaced relation to its inner, annular wall by spaced bearings, packing means associated with the shaft and cup-shaped member to confine a space surrounding a mid-section of portion and extending into close proximity to the inner'surface of said snout, openings in the conical hub located rearwardly of the blades thereof and leading to its hollow interior, an axial bore in said shaft communicating with openings leading respectively into the interior of the impeller and into the said confined space surrounding the shaft, whereby air separated from liquid-air mixture in swirling flow imparted by the impeller accumulates close to the impeller and is forced through the openings in the conical hub and into the bore of the shaft, such separated air being subsequently forced by centrifugal blower action of the rotating shaft into the confined space surrounding the shaft, from which confined space it is removed.

EDWARD TOPANELIAN, JR.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,143,957 Hansen June 22, 1915 2,024,703 Ragsdale et a1 Dec. 17, 1935 2,233,825 Walsh et a1. Mar. 4, 1941 2,278,397 Scheibe et a1 Mai. 31, 1942 FOREIGN PATENTS Number Country Date 7,401 Netherlands Aug. 15, 1922 549.670

Great Britain Dec. 2, 1942