US3032258A

US3032258A - Vacuum pumps

Info

Publication number: US3032258A
Authority: US
Inventors: Irving C Jennings
Original assignee: Nash Engineering Co
Current assignee: Nash Engineering Co
Priority date: 1958-09-04
Filing date: 1958-09-04
Publication date: 1962-05-01
Anticipated expiration: 1979-05-01

Description

May 1, 1962 I. C. JENNINGS VACUUM PUMPS Filed Sept. 4. 1958 INVENTOR Rum 4; 6. \ZbvM/vqs ATTO NEY5 United States Patent Office 7 3,932,253 Patented May 1, 1962 3,032,258 VACUUM PUMPS Irving C. Jennings, Nash Engineering Company, South Norwallr, Conn. Filed Sept. 4, 1958, Ser. No. 758,948 Claims. (Cl. 230-79) This invention relates in general to hydro-turbine vacuum type pumps and pump systems and particularly to a new and useful hydro-turbine pump and an improved liquid supply system therefor.

A hydro-turbine pump of the character with which this invention is concerned includes a pumping chamber including two lobed portions separated by land portions in which a symmetrical rotor is rotated. A small quantity of liquid is introduced into the pumping chamber and its movement around the lobed and land portions effects the drawing in of a quantity of gas or gas and vapor mixture into the pump at locations where the liquid is directed from the land to the lobed portions and efiects a compression of the gases in areas where the liquid is directed from the lobed to the land portions. It is an important characteristic of such pumps that when operating at high vacuum suction conditions the pump requires a greater amount of liquid in the liquid ring than is necessary when operating at low vacuum. To provide for these changed requirements for the liquid ring volume of such pumps, such devices as float operated supply tanks have been provided. An obvious disadvantage of such supply tanks is that the ball float must be maintained in an operating condition and periodically checked to insure its correct functioning. Such devices do not readily effect a controlled supply of liquid to the pump when its service vacuum requirements are changed.

Where the liquid supply for such vacuum pumps is obtained directly from city operated water mains it is important, and usually sanitary codes require, that a break be provided between the fresh water supply and the pump inlet in order to prevent any possibility of contaminated water backing up into the city water supply. Since the make-up liquid for vacuum pumps is normally introduced at the inlet, which is under vacuum, it is not practical to have a vacuum break between the water supply and the connection to the pump without having some means to prevent air from being drawn into the pump.

In accordance with the present invention, there is provided a simple vacuum pump construction and vacuum pump liquid supply system including a combination discharge separating tank and constant liquid level supply tank, which functions as a receiver for the discharge of the vacuum pump and as a liquid reservoir source supplying liquid to the pump under its various conditions of operation. The apparatus includes an inlet orifice to which make-up water must flow from the separating tank and the liquid main connection. The arrangement is such that pressure in the separating tank is maintained constant and therefore variations in the pressures of operation of the suction pump will cause greater or less flow directly in proportion to the increase or decrease in suction vacuum being maintained in the pump. The apparatus further includes a vacuum break in the connection to the city main supply.

Accordingly, it is an object of this invention to, provide an improved hydro-turbine vacuum pump having a liquid inlet arranged to efiect liquid flow in proportion to the operating conditions of the pump.

A further object of the invention is to provide a hydro-turbine pump including a combination constant level and a discharge separating tank into which the pump discharges and to which is connected a liquid supply and overflow for maintaining the liquid therein at constant levels as well as to keep the liquid cool; and a liquid inlet for such pump, including an orifice through which make-up liquid flows and a connection therefrom to said separating tank.

A further object of this invention is to provide a hydro-turbine liquid supply system which is simple in design, rugged in construction and economical to manufacture.

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 attained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.

In the drawings:

FIG. 1 is a somewhat schematic view partly in section of a hydro-turbine pump liquid supply system constructed in accordance with the invention; and

FIG. 2 is a transverse section of the pump indicated in FIG. 1 indicating the end casing inlet and outlet passage construction and the pumping portion of the pump.

Referring to the drawings in particular, the invention as embodied therein includes a hydro-turbine suction pump generally designated A having at one end thereof an inlet 10 at one side, and a discharge 12 at the opposite side arranged to discharge into a constant level separating tank B. The tank B is supplied with liquid from a water main conduit 14 through a solenoid valve l6, a manually operated valve 17, conduit 18, a vacuum break generally designated C, and a U-sh-aped conduit 20. Liquid 22 is maintained at a constant level within the constant level separating tank B, and is discharged therefrom through a discharge connection 23 located above the bottom wall of the tank at desired liquid level. The valve 17 is cracked open a sufficient amount to maintain a small overflow through the discharge 23. The tank discharges vapors or gases through a conduit 25 located near the top thereof.

The liquid ring suction pump A includes a pumping chamber 24 defined by housing walls forming

opposite lobed sections

26 and 28 and

opposite land sections

30 and 32. A rotor having a plurality of symmetrical blades 34 rotates within the chamber to effect movement of a ring of liquid in the vicinity of the walls of the lobed sections and land sections.

The rotor is constructed with a hollowed central portion which communicates with a ported cone member generally designated 36.

The ported cone member 36 includes two diametrically opposite inlet ports 38 and 4t and two diametrically

opposite discharge ports

42 and 44 which are arranged centrally of the rotor in positions to draw in gases through the inlet as the liquid of the liquid ring is directed outwardly toward the lobed portions and to discharge the compressed gases as the liquid is being directed inwardly from the lobed portions to the land portions.

In accordance with the invention the end housing members or heads of the pump generally designated 46, are formed of a singular annular casting including walls defining a separate inlet passage 48 in communication with the inlet conduit and the ports 38 and 40, and a separate discharge passage 50 in communication with the discharge 12 and the

ports

42 and 44. In addition to the separate inlet and discharge passages formed in the head 46, a separate liquid supply passage 52 is formed therein having a narrowed opening 54 which communicates with a central annular area 56 having opposite ports 58 and 66 which communicate with the inlet ports 38 and 4t) and inlet passage 48.

The inlet passage 52 communicates with a liquid supply inlet 62 which is connected through the lowermost portion of the U-shaped conduit 20. The inlet passage 52 and the inlet 62 are separated by an orifice plate 64 having a central opening 66 chosen for the amount of liquid fiow therethrough desired under given pressure operating conditions.

With the arrangement described when the pump A is operating at high vacuums and consequently higher speeds the pressure difference between the interior of the pump and the interior of the separating and constant level tank B will increase, since the tank B is maintained at atmospheric pressure. Likewise, where there is a low vacuum in the pump A, only a small differential of pressure occurs across the orifice plate 64 and only a small amount of water will flow into the pump. As the vacuum increases this differential increases and more water will flow into the pump, thus providing the larger quantity of liquid required when the pump is producing higher vacuum.

An important feature of the invention lies in the fact:

that all the water drawn from the separator B into the vacuum pump is returned to the separator. Thus, variation in the quantity of water flowing through the pump will not affect the level in the separator B.

The solenoid operated valve 16 is provided to turn the seal water on when the pump starts. This seal water flows into the funnel of the break C and then by gravity into the separator tank B, and is discharged when its level exceeds the level of discharge 23. The quantity of water that flows through the separator B has no relation to the amount of water that the vacuum pump A receives, therefore, variations in the water main pressure do not effect the operation of the pump A. Even if the water supply to the pump were temporarily shut off the vacuum pump A would continue to function until the water in the separator B was gradually lost by evaporation.

The vacuum break C comprises a bulb-like member- 70 having a top opening 72 which receives the bottom end of the conduit 18. The conduit 18 extends downwardly well into the bulb-like member 70 but is spaced from an inlet 74 to the top of the conduit 20. Liquid flows from the conduit 18 into the bulb-like member 70 and downwardly to the outlet 74 at the bottom end thereof. The vacuum break C functions to prevent seal liquid from being sucked upward through the conduit and into the conduit 18 and the city main 14. Thus it is apparent that any suction in the city main will not be contaminated by the pump seal water as air alone. will be sucked in the conduit 18.

Thus, the invention provides a very simple system for the maintaining of the correct amount of liquid in a liquid ring type suction pump. No moving parts are.- required and hence maintenance of the system is very simple. The invention is particularly applicable to a Nash-type water ring pump but may be used for any type vacuum pump requiring a water seal introduced at the inlet.

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.

I claim:

1. In a liquid ring pump including a housing defining a pumping chamber including at least one lobed portion and at least one land portion and a rotor rotatable in said housing, and gaseous inlet and discharge means defined in said housing, the improvement comprising a liquid inlet for the liquid ring of said pump in communication with said gaseous inlet, a constant level liquid supply connected to said liquid inlet, and orifice means at the connection between said liquid supply and said inlet whereby liquid is fed to said pump in proportion to the difierence in pressure between the interior of the pump housing and the constant level liquid supply.

2. The combination of claim 1 wherein said constant level liquid supply includes a separating tank, means for feeding liquid to said tank, means for discharging liquid therefrom when it reaches a predetermined level, and means for connecting said tank to said liquid inlet.

3. The combination according to claim 2 wherein said means for supplying liquid to said tank includes a water main, conduit means connecting said water main to said tank including a vacuum break in said conduit means.

4. A hydro-turbine pump liquid supply system comprising a constant level separating tank, a hydro-turbine pump having an inlet and a discharge, means to discharge said pump into said separating tank, means connecting said tank below the liquid level therein to the inlet of said pump, said connecting means including an orifice restricting the flow of liquid therethrough whereby liquid is supplied to said pump in proportion to the pressure difference between the inlet of said pump and the pressure of said separating tank.

5. The liquid supply system according to claim 4 including means for supplying liquid to said separating tank and overflow means connected to said tank to .discharge liquid therein which rises above a certain level therein.

6. A hydro-turbine pump comprising casing means defining a pumping chamber having at least one lobed portion and at least one land portion, a rotor rotatable within said pumping chamber, a liquid inlet connecting said pumping chamber to supply liquid thereto, an inlet connecting said pumping chamber, a combination constant liquid level supply and separating tank, .a discharge connecting said pumping chamber and said constant liquid level supply and separating tank, and liquid inlet conduit means connecting said tank to said liquid inlet including an orifice separating said tank and said liquid inlet whereby liquid flow from said tank to said pump is in proportion to the pressure difference between said pump and said tank.

7. The liquid ring pump according to claim 6 including means for continuously supplying liquid to said tank and means for discharging liquid therefrom which rises above a certain level.

8. The liquid ring pump according to claim 7 wherein said liquid supply means includes a substantially U-shaped supply conduit and said inlet means includes a conduit connected to the lowermost portion of said U-shaped supply conduit.

9. A seal liquid supply system for a hydro-turbine compressor pump comprising a liquid supply tank, a discharge extending outwardly from said tank intermediate the height thereof, means to direct relatively cool liquid from a water supply main into said tank at a location below said discharge at a predetermined constant rate to maintain a small fiow of liquid outwardly through said discharge at all times during pump operation, and a seal liquid supply conduit for the hydro-turbine compressor pump extending from said tank below said discharge whereby a constant supply of cool liquid at substantially constant pressure is directed to the pump.

10. A supply system according to claim 9 wherein said means for directing liquid to said tank includes a source of liquid under pressure, a substantially U-shaped conduit extending between said liquid pressure source and said tank and wherein said seal liquid supply conduit is connected to the lower end of said substantially 5 U-shaped conduit and to the pump.

References Cited in the file of this patent UNITED STATES PATENTS 1,475,504 Osbourn Nov. 27, 1923 10 6 Wade Nov. 17, 1936 Dodge Nov. 9, 1937 Ramey June 23, 1942 Schmidt Feb. 8, 1944 Cline Nov. 2, 1948 Terrell Jan. 15, 1952 Lawlor May 1, 1956 FOREIGN PATENTS Belgium Oct. 15, 1953