US3213794A

US3213794A - Centrifugal pump with gas separation means

Info

Publication number: US3213794A
Application number: US170673A
Authority: US
Inventors: Harold E Adams
Original assignee: Nash Engineering Co
Current assignee: Nash Engineering Co
Priority date: 1962-02-02
Filing date: 1962-02-02
Publication date: 1965-10-26
Anticipated expiration: 1982-10-26

Description

Oct. 26, 1965 H. E. ADAMS CENTRIFUGAL PUMP WITH GAS SEPARATION MEANS 3 Sheets-Sheet 1 Filed Feb. 2 1962 R. mm u m4 5 0 B00 2 4 2 4 m J 0 W AI f M o0 m: w /l AV RY I BY WMM/j 70%, 7M

TTOF/VEYS Oct. 26, 1965 H. E. ADAMS 3,213,794

CENTRIFUGAL PUMP WITH GAS SEPARATION MEANS Filed Feb. 2, 1962 3 Sheets-Sheet 2 BY 77h12@ 7%@ f 7f3@ ATTORNEYS Oct. 26, 1965 H. E. ADAMS 3,213,794

CENTRIFUGAL PUMP WITH GAS SEPARATION MEANS Filed Feb. 2, 1962 5 Sheets-Sheet 5 lNvENToR /fmcup E. ,40g/ws ATTORNEYS United States Patent O 3,213,794 CENTRFUGAL PUMP WETH GAS SEPARATION MEANS Harold E. Adams, South Norwalk, Conn., assigner to The Nash Engineering Company, a corporation of Connecticut Fiied Feb. 2, 1962, Ser. No. 170,673 7 Claims. (Cl. 103-5) This invention relates to improvements in pumps in general, and in particular to an improved vapor and liquid separating structure for a pump having the capacity to pump fluids in all phases, whether they be in the liquid, gas or vapor state.

In particular, the present invention is concerned with improvements in pumps of the type shown generally in my prior U.S. Patent No. 2,940,657 issued lune 14, 1960. Pumps of this type employ a liquid ring vapor compression portion in series combination with a centrifugal liquid impeller portion, and are capable of pumping a mixed phase iiuid and delivering the fluid into two separate discharges, one liquid and the other gas or vapor, each portion to a desired higher pressure.

In my aforementioned prior art patent the separation of the gases and non-condensable vapors from the liquid portion occurred on the discharge side of the liquid impeller. Accordingly, when pumping a mixture of liquid and gases, the second stage impeller contributes very little to the overall pressure development of this pump, because of the inability of the impeller portion to produce a high differential pressure when pumping a large percentage of gas. As a result, the first stage or liquid ring compressor portion of the pump, was required to span essentially the complete pressure range between the inlet and outlet of the pump. In cases where the desired delivery pressure of the prior art pump might be equal to the maximum ability of the first stage liquid ring impeller, or even beyond its pressure differential producing ability, the pump might become inoperative when a large quantity of air or gas was handled.

However, when a pump according to my prior patent was required to handle all liquid, the unit would readily span the required differential pressure range, because the second stage centrifugal pump portion was not required to pump a high volume of gas and was accordingly able to operate efficiently over a large pressure differential range, thus leaving very little pressure difference for the first stage liquid ring impeller to produce.

According to the present invention, some of the aforesaid operational characteristics of a pump according to my prior invention are avoided by providing for the inter-stage discharge of separated gases so that no need for their passage through the centrifugal impeller portion is required. The interstage removal of gases and non-condensable vapors permits the liquid impeller portion of the pump to operate at its full capacity or efficiency as Well as permits the liquid ring compressor portion to operate over its designed compression ratio range. By thus removing the air or gas from an inter-stage point within the pump and thereby leaving the eye of the impeller free of gas, the impeller Will handle only liquid with the result that the overall density within the impeller passageways is kept to a value approaching that of liquid only and thus the impeller is capable of creating a greater pressure differential between its eye and its discharge than it could maintain if it had to operate in the environment of the prior art.

By thus increasing the pressure differential producing ability of this second stage liquid impeller, it takes over a large proportion of the total pressure difference required of the pump in its application between its inlet and discharge, and thus reduces the pressure difference CII 3,213,794 Patented Oct. 26, 1965 ICC requirement of the rst stage liquid ring pump portion. This relationship, therefore, automatically balances the load between the first and second stages allowing the compressed gas to be discharged at a lower intermediate pressure, which is more commensurate with the capability of the first stage liquid ring pump and allows the second stage centrifugal impeller to handle its designed liquid quantities over its designed pressure range.

Accordingly, a principal object of the present invention is to provide for the interstage discharge of gases and non-condensable vapors in a pump of the type described and thereby provide full second stage performance by the liquid impeller portion while at the same time reducing the pressure differential over which the first stage liquid compressor portion must operate.

This principal object is accomplished by the provision of a novel vapor-liquid separator construction employing a plurality of inclined passageways strategically placed through a central portion of the liquid impeller wall. These passageways function to centripetally separate the gas and vapors near the eye of the impeller. Vapor and liquid separation is further enhanced in the novel construction by a second plurality lof passageways, located radially outward from the first passageways, which communicate through a Wall of the impeller with an annular sealing chamber to drain any liquid therefrom back to the working side of the impeller and thereby prevent flow of said liquid into the vapor and gas discharge portion of the pump.

In addition, the present invention employs a novel structural arrangement of the various elements thereof to present improved operating eiiciency over the structural arrangement of applicants aforementioned patent. The novel structural arrangement employs a combined impeller-compressor rotor driven by a shaft extending from the impeller side of the rotor to a suitable motor means. This arrangement permits maximum area inlet and outlet port cylinder passages for directing inlet liquid and vapor into and away from the liquid ring compressor portion on the pump, because the port cylinder need not be obstructed with the passage therethrough of the rotor drive shaft in view of its previously mentioned connection of the shaft to the impeller side of the rotor. This structural arrangement is a considerable improvement over applicants prior art structural arrangement in his aforementioned issued patent in that increased area inlet and outlet passages are permitted within the port cylinder for delivery of fluid to the liquid ring pump.

Another object of the invention is to provide interstage discharge of separated gases so that improved operating conditions for both the first stage compressor and the second stage liquid impeller result when handling combinations of liquids and gases.

Accordingly, an object of the invention is to provide a pump including improved means for separating the discharge liquids from the discharged vapors and gases.

Yet another object of the invention is to provide an improved centrifugal impeller construction having means for separating vapor and gases from the liquid being pumped thereby.

Yet another important feature of the invention is to provide an improved impeller construction incorporating a plurality of apertures therethrough, strategically located with respect to the blades upon said impeller,

so that improved liquid and vapor separation is accomplished.

Yet another object of the invention is to provide a novel structural arrangement for a pump including a lobed liquid ring vapor compression portion and a certifugal impeller portion connected in series arrangement for pumping fluids in both a liquid and a vapor or gas state or any combination thereof.

Yet another object of the invention is to provide an improved pump of the character described wherein the lobed liquid ring vapor compression portion thereof is provided with a central port cylinder which is unobstructed by the rotor drive shaft and includes inlet passages extending therein on one side thereof and outlet passages extending therefrom on the opposite side thereof.

Another object of the invention is to provide a pump for two-phase mixtures having large straight-through passageways in the central port cylinder unrestricted by passage therethrough of the rotor-impeller drive shaft.

These Yand other objects and advantages of the invention will become apparent and the invention will be fully understood from the following description and drawings, in which:

FIG. 1 is a vertical cross-section of a pump embodying the invention;

FIG. 2 is a cross-sectional View taken along line 2-2 of FIG. l;

FIG. 3 is a cross-sectional view taken along line 3 3 of FIG. l; and

FIG. 4 is a cross-sectional view taken along line 4 4 of FIG. 1.

Referring to the drawings in general, and FIG. 1 in particular, the novel pump structure includes a main housing having a volute portion 10, a central lobe portion 12 and an end inlet head portion 14, each of which are rigidly attached to yone another by securing means, such as bolts (not shown). Affixed to the inner face of the head portion 14 is a stationary cylindrical port cyllinder 16, which projects inwardly therefrom into a central portion of an impeller-rotor, shown generally at 18. The impeller-rotor 18 is affixed by a nut 22 to the end `of a drive shaft 20 which may be connected to any suitable drive means, such as a motor (not shown). Secured to an inside portion of the volute casting is an annular seal plate 24 which encloses a double type resilient shaft seal 26, of conventional design, in close leak-preventing contact with the drive shaft extending therethrough.

The foregoing general description is intended merely to afford an over-all comprehension of the basic structural arrangement of applicants novel pump as a prelude to the detailed description of the illustrative structure which follows.

The inlet head portion 14 includes an inlet opening 28 about which a flange 30 extends to all connection therewith of, for instance, a similarly flanged inlet conduit. The inlet 28 communicates with a pair of bifurcated inlet ports 32 formed in the port cylinder 16, which extend radially outward to form inlet passageways to the inner peripheral portion of a plurality of blades 36 formed in the impeller-rotor 18. The blades 36 divide the liquid ring compressor portion of the rotor 18 into a plurality of vapor pumping chambers 34 (FIG. 3). The central lobe portion 12 of the pump housing surrounds the bladed portion of the impellerrotor and includes a pair of opposed lobes 38 separated by intermediate land portions 39. Connected to the head portion 14 is a conduit 44 for introduction of seal liquid into the lobed portion of the pump housing through one or more orifices 46 in a flange portion of the port cylinder 16.

As is Well understood by those skilled in the art, the blades 36 divide the rotor into a series of pockets or chambers 34, which are ope-n at their inner and outer ends. As a particular chamber 34 traverses the extending part of a lobe 38 in the direction of rotation indicated on the drawings, it discharges a portion of seal liquid into the crescent-shaped lobe 38 between the rotor periphery and the housing 12, causing gas and vapor to be sucked into the inner end of the chamber 34 through the inlet 28 and inlet ports 32. As each of the chambers 34 continues to rotate and traverse the decreasing radius part of the lobe 38, liquid from the lobe is forced back into the chamber 34 causing the chamber to become substantially full of liquid once more. This alternate recession of the liquid in each of the chambers and thereafter advance of the liquid back into the chambers during the rotation thereof compresses the gas and vapor therein and causes it to be expelled in compressed form out through a pair of discharge ports 40 on the opposite side of the port cylinder 16 i-nto the central eye area 42 of a plurality of centrifugal impeller blades 48. Each of the impeller blades 48 extends between an outside wall 50 and a wall portion 52 dividing the impeller portion of the impeller-rotor 18 from the rotor portion of the member. Liquid entering the inlet eye 42 of the impeller is centrifugally forced radially outward between the spirally-shaped impeller blades 48, through exit slots 54, into volute discharge chamber 76 and outwardly through liquid discharge opening connected to any suitable discharge conduit by a discharge flange 78.

The novel centrifugal separating aspect of the present invention is accomplished by providing a plurality of inclined passageways 56 through the outside wall portion 5i) of the impeller. The passageways 56 are inclined to the axis of rotation of the impeller and strategically placed so as to pick-off the centripetally separ-ate gas and vapor near the eye of the impeller.

An important feature of the invention is the positioning of the apertures 56 in the angular relationship shown. It will be noted that passageways 56 are positioned so that the fluid flowing in from the blade side of the outside wall 50 is directed radially inward. By directing the ow inwardly, and thus against centrifugal force, there is a further centrifugal separating effect within the passageways 56 which separates out any residual liquid droplets. Bec-ause of the angular inclination of the passageways 56, thus described, the separated liquid is redirected along the outer radial surfaces of these holes back into the impeller blade pumping section. There is thus developed a somewhat circular flow pattern through the passageways 56 due to this centrifugal effect, with the gas being discharged at the inner radius of the passageways 56 into an annular intermediate collection chamber 58, with the liquid being discharged in counter flow back into the bladed section of the impeller.

The separated gas and vapor collecting in the charnber 58 is discharged outwardly through a plurality of arcuate openings 60 (FIGS. 1 and 4) formed in the seal plate 24 into an enlarged vapor discharge chamber 62 within the volute portion 10, `and thereafter outwardly through a vapor discharge conduit 64. The discharge chamber 62 includes a threaded plug 66 at its lower portion whose position obviously may be interchanged with the threaded discharge conduit 64 to give an alternate vapor discharge connection. Plug 66 is also readily removable to allow drainage of any accumulated condensate in the chamber 62.

The impeller portion of applicants novel pump is further provided with novel liquid seal means on the outside of the

wall portions

50 and 52. Outside wall Si) carries concentric inner and outer raised sealing rings, respectively 68 and 70, which protrude outwardly into a corresponding U-shaped annular groove 72 formed in the seal plate 24. The concentric seal rings 68 and 70 form `a U-shaped annular trough 71 therebetween which is vented through apertures 74 to the liquid pumping side of the impeller and thereby prevent flow of higher pressure liquid in chamber 76 into the lower pressure air chamber. The outermost annular ring 7 0 acts as a first defense in holding back the liquid within the chamber 76, and such liquid that may leak by the first sealing ring 70 is collected in the annular space 71 and is permitted to escape therefrom through the apertures 74 back to the working side of the impeller.

A very important aspect of applicants interstage discharge of gases and non-condensable vapors is the strategic placement of the

apertures

56 and 74 within the impeller with respect to the blades 48 located thereon. Aptertures 56 are purposely placed, by suitable rotational indexing in the manufacturing process, to be adjacent the trailing edge of their respective impeller blades 48. The action of the leading edge of the impeller picks up the liquid, exerting pressure on the liquid and causing it to rotate and develop centrifugal force as it passes through the blade passageways 50. On the opposite or following edge of the impeller blade, a suction or lower pressure is normally developed and it is in this backwater Y region or low pressure area that the opening 56 is placed to withdraw air and non-condensable gases which naturally accumulate and are forced to this low pressure area by the centrifugal and other forces exerted on the air, all of which direct such accumulation to this backwater region. It should be also noted that each of apertures 56 is placed radially with respect to the impeller at as small a radius as possible and yet be at the same time placed behind the entering blade.

Similarly, apertures 74 are also strategically placed relative to the trailing edge of their respective impeller blades 48 (see FIG. 2) although at a larger radius than the apertures 56, to be in the best position to withdraw the accumulation of liquid leakage from trough 71. The placing of apertures 74 next to the backside of the impeller blades 48 is to obtain the minimum pressure within the impeller at this radius so as to obtain the maximum pressure difference between the trough 71 and the impeller passageways Si), to facilitate the return of liquid accumulated within the trough 71.

The wall portion 52 shrouding the opposite sides of the impeller blades 48 is ladapted to rotate in close relation to an adjacent wall portion of the lobe housing 12. The outside portion of the wall 52 carries a projecting annular seal ring 8i) which rotates within a U-shaped groove 82 in the lobe portion 12. The complementary relationship of the U-groove 82 with the annular ring 80 provides an effective seal for limiting any leakage of relatively higher pressure liquid in the volute 76 back toward the lobe portion 38 to effectively isolate the respective portions of the pump.

However, to prevent excess leakage of liquid or gas between chamber 76 to the lobe displacement chamber 38 when a pressure differential exists therebetween, additional apertures 84 are provided which connect a chamber 86 to the interior passageway Sil of the impeller. The apertures 84 enter into the impeller passageways 50 at a smaller radius than the outside diameter of the impeller, and therefore into a lower pressure area than the volute chamber 76 as well as lower than the pressure existing in the chamber 86. The apertures 84, in addition to relieving the excess pressure built up in the chamber 86 to the lower pressure area of the impeller, are placed on the trailing or back edge of the impeller blade 48 to take advantage of the still lower pressure existing in this trailing face area in a manner similar in principle to the aforementioned strategic placement of

apertures

56 and 74.

Thus, it can be seen how applicants arrangement has provided for a novel centrifugal vapor and gas separator means for a pump having the capacity to pump liquids, gases and vapors. The centrifugal separating means employs a plurality of inclined passageways which effectively bleed compressed vapor from the inner portions of the impeller pumping chambers without loss of liquid therethrough. The impeller portion of the invention also includes a novel liquid seal means employing a pair of concentric grooves on an outer Wall of the impeller wherein the annular trough-like space between the rings is vented to permit return of any leakage thereto back to the working side of the impeller. Furthermore, the invention has provided a novel multiphase pump arrangement wherein the central port cylinder 16 is not interrupted by the passage of the rotor drive shaft therethrough, thereby enlarging the inlet and discharge ports to yield increased pumping efficiency due to lower frictional losses.

While the invention is disclosed as embodying a cylindrical inlet port 16, it will be readily apparent to those skilled in the art that the said port could be modied to a conical shape, according to the teachings of applicants prior art Patent No. 2,713,968, without departing from the scope of the present invention. Those skilled in the art will also realize that the impeller portion of the present rotor need not necessarily be of the shrouded vane type to employ applicants

novel passageways

56 and 74 and seal rings 68 and 72. Additionally, those skilled in the art will readily appreciate the novel arrangement of strategically placed apertures through a wall portion of the impeller, is equally applicable to the liquid and vapor centrifugal separator art, as well as to the multiphase pump art, and applicant has only described his invention in combination with this particular pump art for purposes of illustration.

While a specific embodiment of the invention has been shown and described in detail to illustrate the application of the inventive principles, it will be understood that the invention may be embodied otherwise without departing from such principles.

What is claimed is:

1. In series pumping combination, a rst stage liquid ring vapor compression pump and a second stage centrifugal impeller liquid pump, said liquid pump including a volute housing, an impeller having a plurality of pumping chambers rotatably mounted in said housing, and means for centrifugally separating vapor from the liquid being pumped by said impeller, said last mentioned means comprising a plurality of passageways in said impeller extending through a wall thereof to vent an inner radial portion of each of said chambers to an outside wall portion of said impeller, and chamber means formed in said volute housing to receive the separated vapor from said passageways, said first stage liquid ring vapor compression pump being sized and proportioned to pump its full displacement volume of intake vapors and gases over the pumps designed pressure range and discharge its compressed vapors and gases to said second stage centrifugal impeller liquid pump, said impeller liquid pump being sized and proportioned relative to said liquid ring vapor compression pump to pump substantially all liquid over the same designed pressure range.

2. Apparatus according to claim 1, wherein an outside wall of said impeller includes sealing means having a pair of spaced concentric annular ribs which project into a U-shaped annular trough portion of said volute housing to inhibit ow of liquid at the periphery of the impeller toward the impeller axis of rotation, and at least one aperture through the impeller wall between said ribs to permit drainage of any liquid collected therebetween back to the impeller chambers.

3. A vapor and liquid pump comprising a housing having a volute portion and an adjacent lobed portion formed therein, a rotor rotatably mounted within said housing, said rotor including a bladed first stage portion adapted to circulate a ring of seal liquid in said lobed portion, and a centrifugal impeller second stage portion adapted to rotate in said volute portion and receive the entire vapor and liquid discharge from said lobed portion, said infpeller second stage portion including a wall, radially extending blades upon said wall defining centrifugal pumping channels therebetween, and a plurality of passageways extending through said wall to place an inner radial portion of each of said channels in communication with the outside surface of said wall, and chamber means in said housing to receive and separately discharge the vapor flowing in said passageways from the liquid owing centrifugally in said channels, said first stage portion being sized and proportioned to pump its full displacement volume of intake vapor over the pumps designed pressure range and discharge the compressed vapor to said second stage portion, said second stage portion being sized and proportioned relative to said rst stage portion to pump substantially all liquid over the same designed pressure range, said passageways being inclined to the axis of rotation of said impeller portion in a direction radially outward toward the wall of said impeller second stage portion carrying said blades.

4. A vapor and liquid pump according to claim 3, wherein the outer surface of said impeller portion Wall includes seal means comprising a pair of spaced concentric sealing ribs formed thereon for inhibiting flow of higher pressure liquid from said volute portion into said chamber means.

5. A vapor and liquid pump according to claim 4, including in addition, at least one passageway through said impeller wall to place the space between said annular ribs in communication with said channels.

6. A pump according to claim Where said last mentioned passageway vents the space between the annular ribs with a relatively low pressure area adjacent the inner portion of said impeller blades.

7. A multi-purpose pump for operation either as a vapor and gas compressor or as a liquid pump exclusively for pumping combinations thereof comprising a housing having a volute portion and an adjacent lobed portion formed therein, a rotor rotatably mounted within said housing, said rotor including a bladed annular first portion adapted to circulate a ring of seal liquid in said lobed portion, and an impeller second portion adapted to rotate in said volute portion and receive the discharge from said lobed portion, said second portion including a plurality of impeller blades secured to an end Wall of said first portion, a circular end wall enclosing said impeller blades to form a closed face type liquid impeller, a plurality of passageways extending through said circular end wall for separating compressed vapor from the inlet of said impeller, said passageways being located about and adjacent the axis of rotation of said rotor and being inclined to said axis of rotation in a direction so that the inner end of each of said passageways is at a greater radial distance from the rotor axis of rotation than the outside ends of said passageways, seal means cooperative between the end wall of said impeller and an adjacent portion of said housing, said seal means including a pair of raised concentric annular rings and at least one aperture therebetween extending through the impeller end wall, said rings being at a greater radial distance from said rotor axis of rotation than said pasageways, inlet port means secured to one end of said housing extending axially within a central portion of said rotor rst portion for conducting gases and liquids to said lobed portion, a rotor drive shaft extending through the opposite end of said housing secured to the impeller end wall, vapor and gas collection chamber means in communication with the outer end portions of said pasageways, and liquid discharge means connected to said volute portion for conducting liquid therefrom, said lobed portion and cooperative rotor rst portion being sized and proportioned to pump its full displacement volume of intake vapors and gases over said pumps designed pressure range and discharge said compressed vapors and gasses to said volute portion and cooperative rotor second portion, said second portion being sized and proportioned relative to said rst portion to pump substantially all liquid over the same designed pressure range.

References Cited by the Examiner UNITED STATES PATENTS 1,797,810 3/31 Vogel 103-112 1,901,154 3/33 Durdin 103-5 1,946,212 2/34 Jacobsen 103-113 l 1,986,706 1/35 Beyer 103-111 2,758,815 8/56 Fontaine et al 103-113 2,761,393 9/56 De Stefano et al. l 103-113 2,940,657 `6/60 Adams 230-79 FOREIGN PATENTS 404,281 10/ 24 Germany.

462,232 7/ 28 Germany.

838,859 5/52 Germany.

KARL I. ALBRECHT, Primary Examiner.

JOSEPH H. BRANSON, JR., Examiner.

Claims

1. IN SERIES PUMPING COMBINATION, A FIRST STATE LIQUID RING VAPOR COMPRESSION PUMP AND A SECOND STAGE CENTRIFUGAL IMPELLER LIQUID PUMP, SAID LIQUID PUMP INCLUDING A VOLUTE HOUSING, AN IMPELLER HAVING A PLURALITY OF PUMPING CHAMBERS ROTATABLY MOUNTED IN SAID HOUSING, AND MEANS FOR CENTRIFUGALLY SEPARATING VAPOR FROM THE LIQUID BEING PUMPED BY SAID IMPELLER, SAID LAST MENTIONED MEANS COMPRISING A PLURALITY OF PASSAGEWAYS IN SAID IMPELLER EXTENDING THROUGH A WALL THEREOF TO VENT AN INNER RADIAL PORTION OF EACH OF SAID CHAMBERS TO AN OUTSIDE WALL PORTION OF SAID IMPELLER, AND CHAMBER MEANS FORMED IN SAID VOLUTE HOUSING TO RECEIVE THE SEPARATED VAPOR FROM SAID PASSAGEWAYS, SAID FIRST STAGE LIQUID RING VAPOR FROM SAID PUMP BEING SIZED AND PROPORTIONED TO PUMP ITS FULL DISPLACEMENT VOLUME OF INTAKE VAPORS AND GASES OVER THE PUMP''S DESIGNED PRESSURE RANGE AND DISCHARGE ITS COMPRESSED VAPORS AND GASES TO SAID SECOND STAGE CENTRIFUGAL IMPELLER LIQUID PUMP, SAID IMPELLER LIQUID PUMP BEING SIZED AND PROPORTIONED RELATIVE TO SAID LIQUID RING VAPOR COMPRESSION PUMP TO PUMP SUBSTANTIALLY ALL LIQUID OVER THE SAME DESIGNED PRESSURE RANGE.