US3221659A

US3221659A - Liquid ring and centrifugal series pumps for varying density fluids

Info

Publication number: US3221659A
Application number: US261557A
Authority: US
Inventors: Harold E Adams
Original assignee: Nash Engineering Co
Current assignee: Nash Engineering Co
Priority date: 1960-04-20
Filing date: 1963-02-20
Publication date: 1965-12-07
Anticipated expiration: 1982-12-07

Description

Dec. 7, 1965 H. E. ADAMS 3,221,659

LIQUID RING AND CENTRIFUGAL SERIES PUMPS FOR VARYING DENSITY FLUIDS Original Filed April 20, 1960 3 Sheets-Sheet 1 L A I; 44

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INVENTO 644mm 5 04m flazw 949x12 ATTORNEY-5 Dec. 7, E. LIQUID RING AND CENTRIFUGAL SERIES PUMPS FOR VARYING DENSITY FLUIDS Original Filed April 20, 1960 3 Sheets-Sheet 2 INVENTO 5 4/0019 [204! NEYS H. E. ADAMS Dec. 7, 1965 TRIFUGAL SERIES PUMPS DENSITY FLUIDS 3 Sheets-Sheet 5 ND GEN RYING LIQUID RING A FOR VA Original Filed April 20, 1960 INVENTO 69mm 13m;

United States Patent 3,221,659 LIQUID RING AND CENTRIFUGAL SERIES PUMPS FOR VARYING DENSITY FLUIDS Harold E. Adams, South Nor-walk, Conn., assignor to Nash Engineering Company, South Norwalk, Conn., a corporation. of Connecticut Original application Apr. 20, 1960, Ser. No. 23,552, now Patent No. 3,102,083, dated Aug. 27, 1963. Divided and this application Feb. 20, 1963, Ser. No. 261,557

16 Claims. (Cl. 103-5) The present invention concerns improvements in pumps of the type shown in applicants prior U.S. Letters Patent No. 2,940,657, issued June 14, 1960,. and is a division of applicants copending application Serial No. 23,552, filed April 20, 1960 now Patent No. 3,102,083.

This invention relates in general to pumps and in particular to a new and useful centrifugal-displacement type pump, capable of eflicient operation when handling either gases, vapors, or liquids, or a combination thereof.

More specifically the invention concerns improvements in the mechanical arrangement and proportioning of the elements of a pump of this general type which permits more efficient and higher capacity operation over a wide range of fluid states extending from 100% liquid to 100% vapor and gas or any combination thereof.

In pumps of this kind, a pumping chamber is commonly defined by an external casing and an internal ported member of circular cross-sectiomof either conicalor cylindrical shape. The casing is formed to provide one or more lobes and lands in alternation. A rotor, divided into pockets or displacement chambers, surrounds the ported member and drives a ring of water which is caused to surge outwardly and inwardly alternately, and which constitutes the pumping means. The port-ed member is provided with an individual inlet passageway and an outlet passageway for each lobe, and since there are two lobes in the embodiment illustrated, this means that four passageways have to be confined in the volume of the central ported member. It should be understood, however, that while the following description describes applicants novel rearrangement of the elements of the prior art with respect to a two-lobe pump design, that this rearrangement accomplishes similar novel advantages when applied to a single lobe pump design.

For any given size pump having a predetermined rotor outside diameter, the central ported member is kept as small in diameter as possible in order to obtain a favorable ratio of outside to inside rotor diameter. In other words, the smaller the central port member is, the larger the effective radial depth of each of the displacement chambers; and this, in effect, results in an increased stroke for the liquid alternately receding and returning within said chambers. Within this constricted central port member, passageways are provided which conduct the mixture of gas, vapor and liquid to each of the inlet ports and similar conduits within this same confined area conduct these mixtures from the other two outlet ports. There is, therefore, a congestion of passageways all of which pass through the limited diameter of the port member.

In the arrangement described in applicants prior patent, this congestion of passageways within the central port member was further aggravated by the fact that the rotor drive shaft extended directly therethrough and subtracted from the total volume available for the passageways per se. Obviously, the disposition of the rotor drive shaft through this critical area of the pump necessitated a larger central port outside diameter for the same passageway capacity which, therefore, subtracted from the rotor displacement chamber depth with a resultant decrease in the overall pump capacity for its given external dimensions.

In accordance with the novel arrangement aspect of the present invention, the drive shaft enters the pump casing from the side opposite the central ported member. The end of the drive shaft is secured directly to the disc shaped end wall of the centrifugal impeller portion of the pump without interference with the liquid ring compressor portion of the pump adjacent thereto.

In accordance with the novel relative sizing of the first and second pumping stages, the first stage liquid ring is proportioned to pump and compress its full displacement volume of gases over the entire designed pressure range such as from a high vacuum to a few pounds above atimospheric pressure. The second stage centrifugal impeller is proportioned to handle liquid somewhat diluted by air over this same complete pressure range. When a liquid ring compressor and a centrifugal impeller so proportioned are combined in series connected two-stage relationship, the resulting staged combination is capable of handling either gas or 100% liquid, or any mixture thereof, over the complete pressure differential range for which the unit was designed.

Accordingly, it is a principal object of the present invention to provide a pump of the type described having a central port member for the vapor compressor portion thereof totally unobstructed by the rotor drive shaft.

It is another object of the invention to provide a single pump unit with the capability of efiicient pumping over a desired pressure differential of a wide range of fluid states extending from 100% liquid to 100% vapor and gas or any combination thereof.

It is another object of the invention to increase a pumping capacity which may be obtained from a given rotor size.

Another object of the inventionis to provide a simplified central port casting of increased rigidity.

Another object of the invention is to provide a pump of the type described which is more economical to pro duce.

Another object of the invention is to provide an improved combined vapor compressor rotor and centrifugal liquid impeller for a pump which is extremely rigid. and integral in design.

Another object of the invention is to provide an improved centrifugal seal between the vapor pumping portion and the liquid pumping portion of the type of pump described.

The many desirable features of this invention are of particular advantage in a novel combination of a liquid ring air compressor and a centrifugal liquid pump in series relationship so that each pumping element is able to operate under conditions previously considered impossible. It would normally not be expected that such a combination would be practical as you would not expect to place a centrifugal liquid pump as a second stage to an air compressor because, as is well known in the art, centrifugal liquid pumps are allergic to any air entering the suction.

The basic liquid ring pump or compressor is well known in the art and needs no detailed description here. It is designed to pump and compress air or gas by the displacing action of its liquid ring as this ring is driven by a rotor within an eccentric or elliptical casing. The kinetic energy given to the liquid ring is given up or transformed into the work of compression on the gas handled by it. The gas, because of its relatively light density, is handled through the pumps passageways by the displacing action described before, at velocities in the order of from 2000 to 5000 feet per minute, as is common practice with air and gas compressors.

It is well known in the art that a machine to compress gas is inappropriate to handle liquid at the same rate and discharge pressure. The liquid cannot be handled at the same velocities that are permissible with gas. This is because of the great discrepancy in densities between gases and liquid. If a positive type compressor such as a piston pump were to receive solid water at its suction instead of gas, during its normal operation, it would result in either stopping the pump immediately or possibly blowing out its cylinder head or in other ways damaging the pump. If a conventional liquid ring pump is called upon to pump liquid alone at this same high velocity range of 2,000 to 5,000 feet per minute, which of course it will try to do, the pump would not stop or break, as would be the case with a positive pump, but, instead, there is a sudden high surge in power and the pump would cavitate. This action on a liquid ring pump is sometimes referred to as queering or stalling. If allowed to run any length of time in this condition, it would result in damage to the rotor blades and the pump casing by cavitation. Thus, a conventional liquid ring pump must always be supplied with air to prevent mechanical failure.

In view of the above phenomena, a liquid ring pump in the past has never intentionally been used on an application where its suction is liable to be shut off entirely or where air or gas are prevented from entering its inlet because of the lack of such gas. Such would be the case when the pump is used to remove the air and non-condensibles from the condenser in an evaporative system. As soon as most of the air in the condenser is removed, and the condition of virtually no gas flow occurs, the vacuum pump or compressor fills up with its cooling and sealing liquid and the turbulent or queering action results. The resulting destructive action, as stated above, is largely caused by cavitation on the interior parts rather than by failure from high structural stresses, as would be the case of a positive displacement type pump.

In the combination of the invention, provision is made for the liquid ring compressor to also pump liquid only, without air, and without resulting cavitation or damage to the pump or compressor.

It is well known in the art that a centrifugal liquid pump cannot pump if there is any appreciable percentage of air by volume in the mixture entering its suction. In a standard centrifugal pump, this limit is approximately 3% by volume of air to liquid. This is also true if vapor is present in the suction. To avoid the presence of vapor, the suction is always pressurized sufficiently to suppress any vaporization occurring at the inlet. The amount of this pressurization is currently referred to as NPSH, or, net positive suction head above the vapor pressure of the liquid under the conditions at which it arrives at the pump suction. Conventional centrifugal pumps require about 20 feet net positive suction head for uninterrupted pumping. The best centrifugal condenser pumps designed for this condition will operate satisfactorily with about 4 foot suction head as a minimum. Some special purpose centrifugal condenser pumps have been designed for operation at as low as 2 feet net positive suction head, but this is usually at a considerably reduced capacity for the size of the pump involved.

In this invention there is provided a high capacity and efficient combination of a centrifugal liquid pump and a liquid ring pump to pump liquids at their boil point or at zero net positive suction head. This novel combination of liquid ring pump and centrifugal liquid pump in the manner later described thus provides one centrifugal type machine capable of pumping gases, vapors, liquids, or combinations of these, efficiently and with a minimum suction head without damage to the pump structure.

Prior to the present invention, it was considered impractical to take advantage of the generally desirable standard liquid ring vacuum pump for condenser air removal service. This difficulty was principally because the air quantity to be removed from the condenser is sometimes so low that the vacuum pump is operating at virtually zero capacity. Under this condition, the standard liquid ring pump is liable to queer with resultant damage to the pump due to cavitation produced when attempting to pump liquid without air, as has been previously described. The pump combination of this invention, which includes the desirable features of the liquid ring pump and a centrifugal pump, will operate under this zero air capacity condition without damage. The combined gas-vapor-liquid pump of the present invention provides automatic adaptation of the characteristics of the liquid ring compressor and the adjacent series connected centrifugal impeller pump to supplement or complement one another so as to cover a wide range of fluid handling well beyond the capability of applicants previously patented pump.

While the pump of applicants prior patent does include an axial flow impeller portion to enhance the flow of seal liquid through the adjacent compressor portion, it should be noted that this portion was provided therein for the principal purpose of picking up and discharging the mixture of seal liquid and compressed vapors from the discharge ports of the central port member and to impel the mixture away therefrom. The arrangement of the pump in applicants prior patent did not provide adequate impeller pumping capacity of the order provided by applicants centrifugal impeller section herein.

Norman liquid ring pumps cannot operate with usable capacity when the liquid supplied to the pump as a sealing liquid approaches the temperature corresponding to the boiling point pressure of the liquid. Such pumps must operate at an absolute pressure considerably above the boiling point pressure, whereas, in the present pump construction, it is possible to operate at high vacuum with inlet seal temperatures approximately the same as the boiling point temperature and with the normal displacement capacity for the air-vapor mixture present.

Another advantage is that the apparatus constructed in accordance with this invention produces a higher vacuum than is possible witha standard liquid ring vacuum pump. The standard liquid ring pump, as has been indicated before, must have some gas or air present at its suction. In other words, there has to be a reasonable partial air or gas pressure available at the suction. This limits the practical operating vacuum, for instance, on single stage operation when using water seal at F. to about 25 inches Hg. The pump cannot operate safely at higher vacuums because of possible dead end operation and queering or cavitation coming into play. The pump of this invention, however, can continue to operate at the shut-off pressure corresponding to the vapor pressure of its seal. It does not have to have air present under this condition for satisfactory operation, as is the case with the standard liquid ring pump. When using 60 F. water as a sealing means, for example, the pump can go to about 29.4 inches vacuum without cavitation damage, as compared to the 25 inches of a standard type.

The pump combination of the invention includes a housing including a lobed pumping chamber or chambers and a liquid pumping chamber, and including a cylindrical liquid ring rotor and a centrifugal liquid impeller of unitary construction mounted on a common drive shaft within the confines of the pumping chambers. The liquid ring pump portion is arranged to take suction directly from the apparatus from which the boiling liquid, the vapors, and gases are to be removed, and to discharge these at an intermediate pressure to the inlet of the liquid impeller. The unitary impeller-rotor is driven by a shaft attached directly to an end wall of the impeller section. The blades of the impeller are formed in the opposite side of this end wall and are enclosed by a center partition wall which serves in connon also as an end wall of the vapor compressor portion of the pump.

In accordance with the invention, the radial blades of the second stage liquid impeller are generally made equal to or larger than the blades of the liquid ring impeller and are also made. larger than would normally .5 be required for merely the pumping of liquid under the expected designed operating head.

The pump is as mentioned previously designed so that the passageways of the first stage liquid ring portion are as large as possible to facilitate the high capacity handling of liquid as well as gases.

The liquid ring rotor and casing are designed to deliver a given displacement volume of gas over a designed intake and discharge pressure differential. In the case of a distillation unit including a condenser, the intake pressure isthat of the condenser, which may be in the order of 29 inches Hg vacuum, more or less, and the discharge pressure would be slightly above atmospheric pressure, including friction drop, etc., possibly2 or 3 pounds gage pressure. Theliquid ring pump also has the built-in capacity to handle in addition to'the gas, the necessary liquid for sealing, cooling, and condensing purposes. The amount of this liquid capacity is still small relative to the total gas displacement volume rating of the liquid ring portion. The diameter of theliquid ring rotor blades, the displacement capacityofthese blades, and the cooperating elliptical casing surrounding them, all are designed to do the aforementioned amount of work when running at a standard motor drive speed. The kinetic energy imparted to the liquid ring by the buckets or blades. of the rotor is just sufficient to do this amount of work with a comfortablemargin. If the pump is fed liquid only at this point, instead of. gas, it could not deliver this liquid over the same total differential because the kinetic energy imparted to the liquid ring would be insufficient. In accordance with the invention, however, the liquid ring is only required to deliver the high density liquid mixture over a small pressure differential compatible with the kinetic energy imparted to the liquid ring.

The centrifugal liquid impeller is designed to operate at the same rotational. speed, of course, and to deliver the required amount of liquid from the condenser at approximately 29 inches vacuum to a higher pressure above atmosphere than that required of the liquid ring portion. This higher pressure is designed into the centrifugal impeller so that it may discharge against atmospheric pressure when handling a dense mixture of air and water having about 20% air by volume.

The liquid ring portion of the invention when handling normal air or gas quantities compresses these to a smaller volume and discharges them into the inlet of the centrifugal impeller. During this operation, the liquid ring pump handles the air and non-condensible gases over the complete designed differential, from the high vacuum to a pressure above atmosphere, as indicated before. Because of the high air content, the centrifugal impeller during this phase of the operation: adds virtually .no appreciable gas pressure difference. In other words, the liquid ring pump drives the gas through the blade passageways of the liquid centrifugal impeller. During this time, however, the liquid centrifugal impeller also functions as did the axial impeller of my prior Patent 2,940,- 657 to relieve the liquid ring. portion by pumping the entrained cooling and sealing. liquid thus relieving the liquid ring portion of the pump from the necessity of forcing this liquid through the passageways by its compressive action.

The rotating passageways of the centrifugal impeller have the further advantage of centrifugally. separating the entrained liquid from the air-liquid mixture delivered to its inlet by the liquid ring portion. By thus separating the liquid from the air it provides a more efficient gas delivery by the fact that this separation reduces the friction drop that would normally be associated with the turbulent flow of a mixture of gases and liquids through a stationary passageway.

In the operation of a pump constructed in accordance with this invention on a condenser, as the amount of air is reduced or the amount of liquid to be handled by the liquid ring pump is relatively increased either by the condensate to be handled or by the amount of recirculation, the density' of the mixture at the discharge of the liquid ring pump is increased. As the proportion of air is further reduced to the total amount of liquid to be handled, the mixture at the inlet of the centrifugal impeller approaches a value where the impeller can impart by its own action a significant pressure difference and at this point of the operation the. centrifugal liquid impeller then begins to operate as a second stage to the liquid ring pump.

As the evacuation of condenser continues and the mixture approaches the dead end condition previously described, resulting in little or no air being present at the discharge of the liquid ring pump, the mixture is sufficiently dense by this time for the centrifugal impeller to pump this liquid over the normally designed-in. pressure differential for the impeller when. operating with liquid. The designed-in liquid head capacity for the centrifugal liquid impeller is purposely made. greater than the differential between the condenser absolute pressure. and atmosphere so as to provide an ample margin of performance, both at the time of pumping dense liquid and at the intermediate point where there is still some air entrained with the liquid. Thus, when this condition occurs on the operation of the condenser,. the centrifugal liquid pump takes over as a second stage to the liquid ring pump, with the result that. the interstage pressure, which is also the liquid ring discharge pressure, is drastically reduced. Under this condition, the liquid ring portion of the combination has only to operate over an inch or two of mercury pressure differential. instead of the full thirty inch or more differential head from the condenser absolute pressure to atmosphere.

Under this very much reduced differential head, which. may be in the order of /2 to 3 inches mercury pressure, the liquid ring. pump has ample kinetic energy delivered. to its ring to discharge all of the liquid coming to it across this reduced pressure differential without slowing down the liquid ring or causing it to go into the stalled or queered condition, as previously described on dead end condition with standard liquid ring pumps.

The pump structure of the invention provides particular benefits in its application to evaporator systems and apparatus, particularly evaporators of the type employed for the recovery of potable drinking water or other liquids used for human consumption. pump construction utilizes the well known principles of the liquid ring compressor and the liquid centrifugal pump wherein no internal lubrication is required. Therefore liquid processed by the pumps will be free from contamination of lubricants or metal particles caused by rubbing contact, which is generally the case with other mechanical types of pumping equipment.

The centrifugal liquid impeller has the built-in characteristic that it is able to operate over the full pressure range when handling liquid. Like all conventional centrifugal pumps, however, it would not have the capability of pumping directly from the condenser to. atmosphere when the absolute pressure of the condenser was approaching the saturation. temperature of the liquid being pumped. The centrifugal impeller in such a case would require a net positive suction head in order to operate satisfactorily. In such an operation, therefore, the structure of the invention provides the net positive suction head required by the action of the liquid ringfirst stage of the combination. This net positive suction thermore, has the ability of pumping liquid at the boil The novel.

point of the liquid over this small differential, whereas, it could not do this if called upon to pump such liquid over a larger or normal compressor differential.

It is well known in the art that the presence, even of small quantities of vapor at the entrance to a normal centrifugal pump, causes a breakdown in its performance. The formation of vapor at the entrance to the centrifugal pump is generally due to a drop in pressure of the liquid, caused by friction in the lines or at the entrance to the pump itself, with the resultant flashing of this vapor. The presence of the vapor reduces the overall density of the mixture within the centrifugal impeller to the point where the centrifugal pump portion cannot generate the required discharge pressure with this lighter mixture. This results in the stalling of the pump, with little or no delivery therefrom.

A standard liquid ring pump, on the other hand, is designed primarily to handle gases, some vapors, and some liquid for cooling purposes. It is primarily a gas handling pump and can handle gas over its normal designed pressure range. If, however, the liquid seal supplied to the pump is at a temperature approaching the seals vaporizing pressure at the inlet to the pump, the additional pressure drop occurring at the entrance to the pump and its ports will cause vaporization of the sealing liquid. This vaporization progressively fills the displacement chambers of the liquid ring pump until it has no capacity to handle additional gas displacement. The flashing of the vapor at the inlet of the standard liquid ring pump occurs as indicated earlier, at an absolute pressure higher than the absolute vaporizing pressure characteristic of the seal used. This action is common to standard liquid ring pumps and is a recognized limitation. Thus it is seen that in this situation the standard liquid ring pump may have air or gas available at its inlet but it is deprived of reaching this gas because of the exessive flashing of vapor from the seal at its inlet. This action also approximates the dead end operating condition, as previously described.

A pump constructed in accordance with the invention includes large passageways unobstructed by the rotor drive shaft to and from the liquid ring portion of the combination, plus a large capacity second stage centrifugal pump, which permits larger quantities of sealing and cooling liquid to be handle as distinguished from the limited amounts of sealing and cooling liquid that may be handled with conventional liquid ring pumps. This provision for greater liquid flow through the pump also provides a relatively lower temperature rise in the liquid ring for the same amount of work of compression and this factor in itself reduces the possibility of flashing in the ring liquid at the intake port. This flashing tendency is further reduced by the large passageways made available so that there is less pressure drop on the incoming gas and liquid.

Reduction in vapor flashing at the inlet is achieved by reducing the pressure differential over which the liquid ring pump has to work in the first stage of the two stage arrangement. This reduction in pressure differential, of course, reduces the amount of work that the liquid ring portion has to perform thereby further reducing the temperature rise in the large flow of liquid through its passageways.

There is a further assist in this operation. There is a slight reduction in the temperature of the liquid ring caused by any flashing or vaporizing at its inlet and, due to the low temperature difference at which the seal is operating, this cooling effect is of more material help than occurs when there are large temperature differences such as exist on a standard liquid ring pump. This cooling effect and the vaporizing of the seal vary with the thermal characteristics of the liquid being handled. This action depends upon the relationship of the latent heat of the liquid to the specific volume of its vapor at the temperature and pressure involved.

In view of the above provisions, such vapor as is flashed at the inlet to the liquid ring pump Combination is smaller than the normal displacement capacity of the pump. The result is that the liquid ring portion handles or shallows its own flashed vapor and still has major capacity for withdrawing further quantities of liquid and vapor into its displacement chambers for compression and delivery to the interstage point. In the process of compression to the interstage point, its average seal temperature is low enough to condense the vapors during this compression cycle. This results in the discharge to the interstage point of stabilized liquid with suflicient net positive suction head at this interstage point for the centrifugal liquid pump to pick it up without flashing and to deliver it to atmosphere or to the desired higher pressure.

Accordingly, it is an object of this invention to provide an improved pump construction capable of handling liquids at inlet pressures approaching the boiling point pressure of the liquid being pumped.

A further object of the invention is to provide a pump capable of pumping liquid with a minimum of net positive suction head.

A further object of the invention is to provide a pump including a lquid ring compressor portion and a centrifirgal liquid pumping portion, arranged for series opera- A further object of the invention is to provide a pump including a liquid ring vacuum pump portion capable of operating with a sealing liquid approaching or equaling the boiling point pressure of the pumps inlet.

A further object of the invention is to provide a liquid ring vacuum pump combination which is capable of opcrating at shut-off or blanked off inlet suction without cavitation damage.

A further object of the invention is to provide a liquid ring pump combination that is capable of handling liquid without cavitation damage.

A further object of the invention is to provide a liquid ring pump and centrifugal liquid pump combination arranged to satisfactorily pump gases, vapors, liquids, or any combination thereof, with satisfactory life and opera- A further object of the invention is to provide a liquid ring vacuum pump or compressor combination with improved efliciency because of the increased space available for the central port passageways.

A further object of the invention is to provide a combinatton pumping unit including a liquid ring vacuum pump and a liquid centrifugal for simultaneously handling liquid through one inlet connection and air or gas through a second inlet connection.

A further object of the invention is to provide an improved liquid and gas pump which is simple in design, rugged in construction, economical in manufacture and eflicient in operation.

The various features of novelty which characterize the invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects obtained by its use, reference should be made to the accompanying drawrugs and descriptive matter in which there are illustrated and described proved embodiments of the invention.

In the drawings:

FIG. 1 is a tranverse section of a vacuum pump according to the invention;

FIG. 2 is a left end elevation of the pump indicated in FIG. 1;

FIG. 3 is a section taken along lines 33 of FIG. 1;

FIG. 4 is a section taken along the lines 4-4 of FIG. 1;

FIG. 5 is a fragmentary transverse action similar to FIG. 1 indicating an alternate embodiment of the compressor inlet portion for the pump indicated in FIG. 1; and

FIG. 6 is a fragmentary transverse section taken along lines 66 of FIG. 2.

In accordance with the invention, the liquid and gas pump 14 includes a substantially cylindrical casing or housing portion generally designated 38 having an end wall 40 which abuts against and is bolted to a motor 34. The end wall 40 includes an opening to receive a shaft 42 of the motor 34. A mechanical shaft seal 44 is located at the opening of the wall 40 surrounding the shaft 42.

Bolted to the opposite end of the housing member 38 is a compressor lobe housing and inlet head generally designated 46. This lobe housing and inlet' head 46 includes an upper inlet passage 48 and a lower inlet passage 50, each of which feeds into separate inlet passages 52a and 52b formed in a cylindrical ported member generally designated 54' which is located at the center of the lobe portion of the housing. The passages 52a and 52b form separate inlets for each lobe of the pump and in this manner it is possible to obtain independent pumping action if desirable. Of course each passage 48" and 50 may be joined within the pump casing to provide only one inlet connection if desired, or the two inlets could be joined by external piping not shown to produce the same result. Iniany event, applicant's multipurpose pump is novel irrespective of the specific form of inlet connection employed.

In this embodiment the housing 46 has substantially elliptical inner walls 56 defining two lobe portions.

In accordance withthe invention there is provided a rotor generally designated 58 which is threaded onto and secured to the shaft 42 for rotation therewith. The rotor includes a hub portion 60, a disc portion 62- extending radially outwardly therefrom, a liquid impeller blade portion 64 extending axially outwardly from the disc member 62, and a liquid ring rotor portion generally designated 66 including end shrouds 68 and 70 and rotor !blades or buckets 72.

In accordance with the invention, the end shroud portion 70 extends axially and radially beyond a shroud seal portion 74 of the housing 46' and includes an inner peripheral wall 70a slightly spaced from an inwardly extended shroud or wall 78 of the housing 38 and a radially extending tip portion 70b to provide a centrifugal liquid sealing chamber 79 between. an annular discharge chamber 80 and the liquid ring pump portion. 66. The annular discharge chamber 80 formed in' the housing 38 is connected by the discharge passage 82 to the final discharge connection 84.

In operation, liquid and. liquid and gas mixtures, and gas are taken in through the

inlets

48 and 50. In order to insure that thereis a quantity of liquid available for condensing and sealing purposes, some liquid discharged by the pump is recirculated through a conduit not shown to the sealing connection 29. (See FIGS. 2 and 6.) It is directed to the seal chamber 96-formed between shroud 68 and casing 46 through sized orifice passage 98 and then into the lobed portion 56. Liquid which is taken into the first stage compressor portion of the pump isdirected around the lobes by the buckets or blades 72 where the alternate inward and outward direction of the ring of liquid is effective to cause a pumping action and compression of the gases. Gas, liquid, and vapor are taken into the inlet passages 52a and 52b (FIG. 3) through: each of the two inlet. ports 83a and 83b defined in the member 54 at the location of the inner end of the 'blades 72, and condensed vapors and compressed gases are delivered through each of the two discharge ports 86a and 86b defined in the cylindrical ported member 54. The ported member 54 includes a discharge passageway 88 which communicates with the inlet or eye 9 of the liquid pumping impeller 58. The impeller discharges the liquid radially outwardly into the annular chamber 80 as described previously.

The sizes of the liquid ring compressor portion 66 and the blades 72 of the rotor 58, as well as the size of the housing 46, are chosen to handle a displacement volume of gas based on a given intake pressure in inches of mercury. It then compresses this volume while it condenses some of the vapor accompanying the gas and liquid and discharges it at substantially atmospheric pressure into the impeller eye 90. The compressor 66, besides being capable of handling this volume of gas which it compresses, is further capable of handling the necessary liquid for sealing purposes and for cooling and condensing purposes. The ratio of the amount of this liquid capacity relative to the gas displacement capability of the pump, however, is very small.

When the liquid ring rotor 66 is handling mostly gas, as in the initial purging operation on a condenser, this gas is compressed within the rotor to the required atmospheric or greater pressure and discharged through its discharge port into the eye 90 of the centrifugal liquid impeller in the normal manner of liquid ring pump operation; This discharged mixture of gas and liquid will have less gas by volume than at the inlets 52a and 52b by the ratio of the compression ratio between inlet and discharge absolute pressures, plus whatever condensing eflect may come into play within the liquid ring pump. During this operation, the liquid ring pump has the capability of discharging the compressed gas through the inlet eye 90 and blade passageways of the centrifugal liquid impeller, through the collecting chamber and out through the final discharge passageways 84. The centrifugal liquid impeller does not impart any appreciable pressure diiference to the gas passing therethrough at this time but it does assist in pumping the liquid which is discharged with the gas by the liquid ring rotor. The

centrifugal impeller also centrifugally separates the liquid from the gas during its passage through the rotating impeller so as to provide a clearer passageway for the gases in their trip through the impeller blades. effect of reducing friction drop which otherwise would be excessive with a turbulent mixture of gas and liquid.

It should be appreciated that in accordance with this invention the size and shape of the buckets 72 in cooperation with the displacement built into the liquid ring as determined by the lobe portion of the housing are chosen to do. the required amount of gas pumping as well as liquid circulating at a standard motor drive speed. The kinetic energy imparted through the blades by the motor 34 is just enough to do this work with a comfortable margin.

During the normal operation on a condenser and after the purging of the condenser of the initial amount of air, there is little or no air to be handled by the liquid ring pump and-it attempts to handle liquid only. The designed proportions of the liquid ring pump portion 66 are such that it does not have sufiicient kinetic energy to handle liquid only over the same pressure differential that it normally handles air. Provision is made in this structure whereby the pressure diflerential is reduced across the liquid ringpump portion 66 when it is called upon to handle liquid only. This is accomplished by the combination therewith of relatively high capacity second stage liquid impeller blades 64. This latter impeller is designed with excess head capacity over and above the pressure head conditions between the head of the intake and the final discharge point, which is slightly above atmospheric pressure.

The. impeller blades 64 are sized to handle a dense liquid-air mixture at normal absolute pressure of the service to which it is to be connected. During the preliminary hogging operation, when the mixture is lighter in density and during which time the liquid pump is handling air, the liquid centrifugal impeller adds virtually no pressure difference to the gas being delivered but as soon as this density is increased by the material reduction in air handled by the liquid ring pump, the

This has the centrifugal liquid impeller blades 64 act as a second stage to the liquid ring rotor, thus reducing the interstage pressure at the discharge ports 86a of the liquid ring compressor, to the point where the differential across the liquid ring compressor is sufliciently lowered such that the liquid ring can deliver solid liquid against this pressure differential without distress and without exceeding the available kinetic energy being delivered to its liquid ring by the motor 34. The liquid impeller blades 64 discharge the dense air-liquid mixture into the volute passage 80 from where it is discharged through passage 82 to the discharge conduit 84 at prescribed head pressure.

While the invention has been shown and described in connection with two lobe vapor pumping portions 56, it should be realized that a single eccentric casing may be used for a single lobe with a single inlet connection and a single discharge connection communicating with the inlet 90 of the second stage liquid impeller or a number of lobes over two may be employed. The single lobe construction may be as indicated in FIG. showing the single inlet connection 92 in direct communication with a single inlet port 52. A single discharge 86 port communicates with the inlet eye 90 of the second stage impeller (not shown).

It should be appreciated that the improved pump construction of the present invention has many other additional applications other than the evaporator system described herein. For example, the pump may be used in a process system for returning drained hot condensate back to a boiler. In such instances, it was usual to use a pump system which includes a jet pump and a centrifu' gal pump arranged to operate in combination. The centrifugal pump draws water from a heat dissipating finned priming loop and discharges through the jet pump which reduces a positive flow of condensate, gas and air from the process equipment drainage line and discharges the condensate directly to the boiler. In such systems, entrained non-condensible gases and air are eliminated from the circuit by means of a separation chamber set-up.

The present pump may replace the jet pump and centrifugal pump combination and operate very efliciently in handling liquids, gases and vapors or any combination thereof.

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

What is claimed is:

1. A multi-purpose pump comprising a housing having an interior compressor portion having at least one lobe, and an interior liquid pumping portion adjacent said compressor portion, inlet means for directing fluids in the gaseous and liquid state to said compressor portion, annular volute discharge means extending about said liquid pumping portion, said compressor portion including, a discharge, a symmetrical annular rotor having radially extending blades and a pair of annular end shrouds forming therewith a plurality of radially extending displacement chambers, said liquid pumping portion including a liquid impeller adjacent said rotor having a plurality of enclosed impeller blades integral with an end shroud of said rotor and shaped to provide a central inlet, whereby to take fluids in centrally from the discharge of said compressor portion and direct said fluids to said volute discharge means, and shaft means connected to said impeller for imparting rotation to said rotor via rotation of said impeller; said compressor portion, and said compressor rotor having a capacity to pump and compress its full displacement volume of intake vapors and gases over said pumps designed pressure range and to discharge said compressed vapors and gases to said impeller, said impeller having a capacity to pump substantially all liquid over the same designed pressure range and to thereby reduce the pressure at the discharge of said compressor portion when substantially no gas and vapor is present at the inlet of said compressor portion whereby said compressor portion is only required to handle substantially all liquid over a greatly reduced pressure range.

2. A pump according to claim 1 wherein said compressor inlet includes central port means having peripheral openings adjacent the inner ends of said displacement chambers.

3. A pump according to claim 2 wherein said compressor portion discharge includes a central port opposite said impeller inlet and including openings communicating with said compressor portion at the inner periphery of said displacement chambers.

4. A pump according to claim 1 wherein said housing includes a wall spaced from an end of said impeller adjacent said compressor rotor and wherein said compressor rotor shroud includes an extended portion arranged to rotate with its periphery closely spaced from said wall, said impeller and said housing defining a sealing passage between said impeller and said compressor rotor.

5. A pump according to claim 1 wherein said inlet means includes a central ported member around which said compressor rotor blades are arranged to rotate, said ported member including a ported opening adjacent the interior of said blades.

6. A pump according to claim 5 wherein said ported member includes a second ported opening substantially diametrically opposite said first ported opening and wherein said compressor pump portion has at least two lobed portions served by a respective ported opening and at least two inlet conduits connecting said ported member openings.

7. A centrifugal displacement pump capable of handling entirely liquid, entirely gas and any combination of gas and liquid comprising, a housing having an interior compressor portion having at least one lobe defined therein, and a liquid pumping portion adjacent said compressor portion including an annular discharge defined therein, a unitary rotor member including a centrifugal blade portion positioned in said liquid pumping portion of said housing, and a compressor rotor portion integrally formed therewith including a multiplicity of symmetrical radially extending blades extending into said compressor portion, inlet conduit means in said housing arranged to direct fluid to said compressor portion in directions radially outwardly into said rotor blades, a discharge conduit defined in said housing connected between the center of said compressor rot-or blades and the center of said centrifugal blade portion for discharging fluids from said compressor portion to said liquid pumping portion; said compressor portion and said liquid pumping portion having respective capacities to permit compression of entirely gases over a predetermined pressure range and handling of entirely liquid by said compressor porton over a greatly reduced pressure range and combined handling of any portion of gases and liquid between a fixed operating pressure range without structural damage to said pump.

8. A centrifugal displacement pump capable of handling liquids at their boiling point and entirely liquid, entirely gas and any combination thereof, comprising a housing having an interior compressor portion with at least one lobe defined therein and an interior liquid pumping portion adjacent said compressor portion, and rotatable rotor means in said housing including a compressor portion for compressing gases from a low pressure to a predetermined higher pressure, and for handling liquid entirely and any proportion of liquid and gas over a pressure range less than its designed compression range, and liquid impeller means arranged to receive the discharge of said compressor and to discharge it at an elevated operating pressure above the high pressure discharge of said compressor, and to reduce the pressure at the discharge of said compressor portion when substantially all liquid is present at the inlet of said compressor portion.

9. A centrifugal displacement pump according to claim 8, including an end casing member having two separate inlets connected to said compressor portion and wherein said compressor portion includes at least two lobed portions having separate inlet means serving each one thereof.

10. A pumping device for use in an industrial process handling liquids and mixtures of said liquids and vapors of said liquids at conditions approaching the boiling point and vapor pressure of such liquids comprising a housing including a liquid pumping portion, a compressor portion adjacent said liquid pumping portion including at least one lobe defined therein, inlet means connected to said compressor portion and discharge means connected to said liquid pumping portion, said liquid pumping portion including a central opening on a side opposite from said compressor portion, rotatable shaft means extending into said opening, an intregal impeller member afiixed to said rotatable shaft means, said member including a centrifugal impeller portion having blades curved to define a central inlet and a radial discharge directed towards said discharge means, and a compressor rotor portion including symmetrical radial buckets arranged in the lobe portion of said compressor portion, central inlet passage means connected to said inlet means and the central portion of said compressor rotor portion and central discharge passage means connected to the central portion of said compressor rotor and said liquid impeller portion.

11. In an industrial process using liquids at pressure and temperature conditions approaching respectively the vapor pressure and the boiling point of said liquid, the improvement comprising a pumping device for pumping such liquids and the vapors of such liquids including a housing having a liquid pumping portion, a compressor portion adjacent said liquid pumping portion including at least one lobe defined therein, inlet means connected to said compressor portion and discharge means connected to said liquid pumping portion, said liquid pumping portion including a central opening on a side opposte from said compressor portion, rotatable shaft means extending into said opening, an integral impeller member affixed to said rotatable shaft means, said member including a centrifugal impeller portion having blades curved to define a central inlet and a radial discharge directed towards said discharge means, and a compressor rotor portion including symmetrical radial buckets arranged in said compressor portion, and central inlet and discharge passage means connecting said inlet means and the central portion of said compressor rotor portion and said liquid impeller portion.

12. A vapor and liquid pump comprising a housing having a volute portion and an adjacent lobed portion formed therein, a rotor pivotally mounted within said housing, said rotor including a bladed portion for circulating a ring of seal liquid in said lobed portion, and an impeller portion mounted for rotation in said volute portion and arranged to receive the discharge from said lobed portion, a rotor drive shaft, said shaft extending through an end portion of said housing adjacent the impeller portion of said rotor and aflixed to said impeller portion, and port means extending axially within a central portion of said bladed portion, said port means being formed interiorly to provide an intake path directly from the end of the housing opposite the end of said housing having said shaft extending therethrough to said bladed portion, and for providing a discharge path directly from the bladed portion to the impeller portion.

13. A pump according to claim 12 wherein the outside diameter of said impeller portion is substantially larger than the outside diameter of said rotor.

14. A pump according to claim 12 wherein the outside diameter of said impeller portion is substantially greater than the peripheral dimension of said lobed portion.

15. A pump according to claim 14 wherein said rotor includes an annular Wall means located between said lobed portion and impeller portion, the outer periphery of said wall means being greater than the outside diameter of said impeller portion, and an annular U-shaped channel within said housing between said lobed portion and said volute portion; said channel being cooperative with said wall means to form a liquid seal between the adjacent portions of said pump.

'16. A vapor and liquid pump according to claim 12, wherein said lobed portion is provided with a capacity adequate to pump and compress its full displacement volume of intake vapors and gases over said pumps designed pressure range and to discharge said compressed vapors and gases to said volute portion, said volute portion being provided with a capacity to pump substantially all liquid over the same designed pressure range and to thereby reduce the pressure at the dis-charge of said lobed portion when substantially no gas and vapor is present at the inlet of said lobed portion whereby said lobed portion is only required to handle substantially all liquid over a greatly reduced pressure range.

References Cited by the Examiner UNITED STATES PATENTS 2,362,954 11/1944 Adams 103-6 2,461,865 2/ 1949 Adams 103-113 2,553,066 5/1951 Southern 103-5 2,940,657 6/1960 Adams 230-79 2,952,214 9/1960 Adams 103-113 3,102,083 8/1963 Adams 103-5 LAURENCE V. EFNER, Primary Examiner.

Claims

1. A MULTI-PURPOSE PUMP COMPRISING A HOUSING HAVING AN INTERIOR COMPRESSOR PORTION HAVING AT LEAST ONE LOBE, AND AN INTERIOR LIQUID PUMPING PORTION ADJACENT SAID COMPRESSOR PORTION, INLET MEANS FOR DIRECTING FLUIDS IN THE GASEOUS AND LIQUID STATE TO SAID COMPRESSOR PORTION, ANNULAR VOLUTE DISCHARGE MEANS EXTENDING ABOUT SAID LIQUID PUMPING PORTION, SAID COMPRESSOR PORTION INCLUDING, A DISCHARGE, A SYMMETRICAL ANNULAR ROTOER HAVING RADIALLY EXTENDING BLADES AND A PAIR OF ANNULAR END SHROUDS FORMING THEREWITH A PLURALITY OF RADIALLY EXTENDING DISPLACEMENT CHAMBERS, SAID LIQUID PUMPING PORTION INCLUDING A LIQUID IMPELLER BLADES INTEGRAL WITH AN END SHROUD OF LIQUID IMPELLER ADJACENT SAID ROTOR HAVING A PLURALITY OF ENCLOSED IMPELLER BLADES INTEGRAL WITH AN END SHROUD OF SAID ROTOR AND SHAPED TO PROVIDE A CENTRAL INLET, WHEREBY TO TAKE FLUIDS IN CENTRALLY FROM THE DISCHARGE OF SAID COMPRESSOR PORTION AND DIRECT SAID FLUIDS TO SAID VOLUTE DISCHARGE MEANS, AND SHAFT MEANS CONNECTED TO SAID IMPELLER FOR IMPARTING ROTATION TO SAID ROTOR VIA ROTATION OF AND IMPELLING; SAID COMPRESSOR PORTION, AND SAID COMPRESSOR ROTOR HAVING A CAPACITY TO PUMP AND COMPRESS ITS FULL DISPLACEMENT VOLUME OF INTAKE VAPORS AND GASES OVER SAID PUMPS DESIGNED PRESSURE RANGE AND TO DISCHARGE SAID COMPRESSED VAPORS AND GASES TO SAID IMPELLER, SAID IMPELLER HAVING A CAPACITY TO PUMP SUBSTANTIALLY ALL LIQUID OVER THE SAME DESIGNED PRESSURE RANGE AND TO THEREBY REDUCE THE PRESSURE AT THE DISCHARGE OF SAID COMPRESSOR PORTION WHEN SUBSTATIALL NO GAS AND VAPOR IS PRESENT AT THE INLET OF SAID COMPRESSOR PORTION WHEREBY SAID COMPRESSOR PORTION IS ONLY REQUIRED TO HANDLE SUBSTANTIALLY ALL LIQUID OVER A GREATLY REDUCED PRESSURE RANGE.