US3306216A - Liquid displacement pressure transfer pump - Google Patents

Description

Feb. 28, 1967 c. H. WARMAN 3,306,216

LIQUID DISPLACEMENT PRESSURE TRANSFER PUMP Filed April 19, 1965 3 Sheets-Sheet 1 i as H l4 20 t f Feb. 28, 1967 c. H. WARMAN 3,306,216 LIQUID DISPLACEMENT PRESSURE TRANSFE Filed April 19, 1965 I R PUMP 3 Sheets-Sheet 2 V zz/jy yM Feb. 28, 1967 c. H. WARMAN LIQUID DISPLACEMENT PRESSURE TRANSFER PUMP Fild April 19 1965 5 $heets-$heet 3 United States Patent ()fifioe 3,305,216 Patented Feb. 28, 1967 3,306 216 LIQUID DIEiPLACEMEN'I PRESSURE TRANSFER UMP This invention relates to liquid displacement pressure transfer pumps of the type wherein one liquid is superposed above another liquid or a slurry of greater specific weight within a displacement vessel provided with valved connections whereby cyclically each of the liquids is separately and alternately admitted to the vessel at a pressure different from the other and each is separately and alternately displaced from the vessel by pressure exerted by the other.

One object of the invention is to provide a liquid displacement pump of the type above described in which the area of direct contact between the liquids is reduced to a very small order so that the opportunity for mixing of the liquids is reduced to a minimum and contamination of one liquid by the other is substantially avoided. This consideration is very important when the liquids are miscible such as for instance when one of the liquids is water and the other a suspension of fine solids in water. Another object is to provide a liquid displacement pump in which such small amount of contamination as may take place is of one of the liquids only and the other passing continuously into it through the small area of communication between them. A further and particular objective is to provide a pump of low cost construction and high efficiency for pumping abrasive or corrosive liquids or slurries against higher heads than are economically possible when using abrasion or corrosion resistant centrifugal pumps. In such applications, using clear water as the superposed liquid, the invention enables high etficiency single or multistage centrifugal water pumps to be employed to supply the necessary pressure energy by providing the means whereby this pressure energy is transferred to the abrasive or corrosive liquid or slurry.

In a pump according to the invention a free piston or separator floats either at and with the interface between, or with and within or adjacent above the confluence of, the two liquids. The floating piston or separator conforms with working clearance to the walls of the enclosing or displacement vessel so that communication between the liquids is restricted to the area of the working clearance. The specific weight of the floating piston or separator may be intermediate between the specific weights of the two liquids or it may be equal to or less than that of the superposed liquid. According to the specific weight of the piston within the abovemen-tioned limits it may float partly in each liquid, entirely in the superposed liquid or, if of lower specific weight than the superposed liquid, rise slowly with respect thereto thus causing, relative to the piston, a downward flow of superposed liquid through the working clearance between the piston and the walls of the displacement vessel.

The most suitable specific weight of piston for any given application is dependent upon the nature of the liquids and the degree of mixing or contamination that can be tolerated in each liquid. If the liquids are immiscible or their tendency to mix is small or negligible the piston serves mainly to avoid mixing by turbulence and entrainment of one in the other arising from their velocities entering the displacement vessel and the piston may float partly in each liquid. If the liquids are miscible,

and particularly if it is desirable or necessary to prevent contamination of the superposed liquid and some dilution of the heavier liquid or slurry by the superposed liquid is permissible, then the specific weight of the piston may With advantage be less than that of the superposed liquid and it is an important feature of this invention that the clearance area between the piston and the walls of the displacement vessel and the relative specific weights of piston and superposed fluid are proportioned with respect to each other to cause the piston to rise relative to the superposed liquid at a predetermined rate.

While the displacement vessel may have a variety of prismatic shapes it is usually a vertical cylinder with end covers to which the valved connections are made. While the floating piston may be prismatic or cylindrical conforming to the cross-section of the displacement vessel it is advantageous and a feature of the invention, when the displacement vessel is a cylinder, for the piston to be spherical to avoid any possibility of its jamming in the cylinder and to provide the best shape to resist collapse under pressure when, as'is usually required to obtain a sufficiently low specific weight, the piston is hollow.

A feature of the invention is that internally the end covers are shaped to conform to, support and make sealing contact with the piston at the limits of its travel, said sealing contact isolating the displacement vessel from the respective end cover valved connections so that neither liquid can pass through the displacement cylinder into the valved connections of the other. Thus when the displacement vessel is a cylinder and the piston spherical the end covers are internally substantially hemispherical and may be provided with a resilient sealing member to afford a liquid tight seal when the piston is seated in an end cover by the pressure of liquid in the displacement vessel. Alternatively, sealing means may be provided in one end cover only.

Wit-h only one displacement vessel the liquid flow rates to and from a displacement type pump vary widely cyclically, even when flow equalising devices are incorporated. To reduce the cyclic variation of the liquid flow rates this invention provides for combining in parallel in one pump a number of displacement mechanisms in constant phase relationship by interconnecting the valved connections of the individual mechanism.

Some specific forms of the invention are illustrated in the accompanying drawings wherein:

FIG. 1 is a diagrammatic section on vertical centreline of the liquid displacement pressure transfer pump.

FIG. 2 is a diagrammatic section on vertical centreline of a variant form of the liquid displacement pressure transfer pump.

FIG. 3 is a cross section on the vertical centreline of the displacement cylinder assembly.

FIG. 4 is a part section on the vertical centreline of the upper region of the displacement cylinder assembly illustrating the piston sealing means.

Like parts are illustrated :by like characters throughout the specification and drawings.

As shown in the drawings 1 is a spherical piston or separator conforming with working clearance to the walls of a displacement cylinder 2, and allowing free movement of the piston along the substantially vertical cylinder axis. The piston 1 floats either at and with the interface between, or with and within or adjacent above the confluence of, liquid 3 and liquid or slurry 4, which are substantially above and below the horizontal diametral plane of said piston respectively. The piston 1 is contained within the displacement cylinder 2 by upper and lower cylinder covers 5 and 6 respectively, each having a substantially hemispherical internal surface to conform closely to the shape of the piston. A seal 7, of a resilient material, is located in the upper cylinder cover 5 concentrically with the vertical axis of the upper cylinder cover and cylindrical Opening 8, and is shaped to bear uniformly over an annular contact area, and in sealing contact with the piston 1 in its upper limiting position, as shown in FIG. 4. The piston 1, displacement cylinder 2, upper and lower cylinder covers 5 and 6 respectively, and seal 7 together form the displacement cylinder assembly 9.

The lower cylinder cover 6 connects, via flanged opening 10 and piping 11, to entry and discharge valve units 12 and 13, respectively. The entry and discharge valve units are comprised of frames 14 and 15 respectively, and valves 16 and 17 respectively which move on substantially vertical centrelines, and bear with sealing contact on valve seats 18 and 19 respectively. Liquid or slurry 4 enters feed opening 20 of entry valve unit 12 in a state of low pressure energy, and discharges from outlet 21 of discharge valve unit 13 in a state of high pressure energy.

In one means of performing the invention, as shown in FIG. 1, a timing valve unit 22 is mounted on flanged opening 8 of the upper cylinder cover 5, and has the function of controlling admission and expulsion of liquid 3 respectively to and from the upper cylinder cover. The timing valve unit 22 is actuated by an external drive unit 23 under the control of which connection is alternately established between the upper cylinder cover 5, and high and low pressure outlets, 24 and 25 respectively, via the interior of said timing valve unit. The frequency of valve operation is directly proportional to the speed of the drive unit 23. Piping 26 connects high pressure outlet 24 to the discharge 27 of a high pressure multi-stage centrifugal pump 28, which is fed from a reservoir 29. Low pressure outlet 25 connects, via piping 30, to reservoir 29.

In a variant means of performing the invention, as shown in FIG. 2, the outlet 8 of the upper cylinder cover 5 connects, via piping 31, to the cylinder 32, enclosing a piston 33, of a reciprocating type of high pressure pump 34, and to the discharge 35 of a check valve unit 36. The valve unit intake 37 connects, via piping 38, to a reservoir 39.

The use and operation of the invention will be considered with reference to FIGS. 1, 2, 3 and 4.

The principal object of the invention is to provide a means of transferring pressure energy from a liquid 3 to a liquid or slurry 4. Transfer of pressure energy takes place within the displacement cylinder assembly 9 to which the liquid 3 is admitted in a state of high pressure energy and discharged in a state of low pressure energy, and the liquid or slurry 4 is admitted in a state of low pressure energy and discharged in a state of high pressure energy. The transfer of pressure energy between liquid 3 and liquid or slurry 4 occurs cyclically, and is accompanied by a reciprocating motion of piston 1 along the axis of the displacement cylinder 2. The upper and lower limiting positions of the piston in the displacement cylinders are indicated by outlines 40 and 41 respectively in FIG. 3.

The liquid 3 and liquid or slurry 4 are separated in the displacement cylinder 2 by the piston 1 which reduces the area of direct contact between the liquids or liquid and slurry, and hence substantially prevents contamination of one liquid or slurry by the other. If the liquids 3 and 4 are immiscible, or their tendency to mix is small or negligible, the piston 1 will float partially in each liquid, and the interface between them will intersect the piston at a vertical position dependent upon the specific weights of the two liquids and the piston. Ideally the specific weight of the piston 1 should be controlled so that the interface between the liquids 3 and 4 intersects the piston at its horizontal diametral plane, thus having minimum area of contact so that contamination of one liquid by the other is substantially minimised.

If the liquid 3 and liquid or slurry 4 are miscible, and particularly if it is desirable or necessary to prevent contamination of the superposed liquid 3, and some dilution of the heavier liquid or slurry 4 by the liquid 3 is permissible, then it is advantageous for the specific weight of the piston 1 to be less than that of the superposed liquid 3. As a consequence of the displacement of liquid 3 by the piston 1, the piston exerts a net buoyant force vertically upwards upon the liquid 3, above the piston, increasing its specific energy thereof above that of liquid or slurry 4- below the piston, and causing a downward flow of liquid 3, relative to the bulk of said liquid, passing through the annular space between piston and walls of the displacement cylinder 2 as shown by arrows 42, and mixing with liquid or slurry 4. The displacement of liquid 3 from above to below the piston 1 induces a corresponding vertically upward motion of the piston, relative to the bulk of liquid 3 and liquid or slurry 4, directed along the axis of the displacement cylinder 2, and with velocity proportional to the rate of displacement of liquid, and to the area of the displacement cylinder. The transfer of liquid 3 across the horizontal diametral plane of the piston 1 and mixing with liquid or slurry 4 continues, throughout the pumping cycle, substantially independently of the vertical velocity of the piston along the axis of the displacement cylinder 2, and the downward flushing action of this liquid flow is instrumental in minimising contamination of liquid 3 by liquid or slurry 4. The effectiveness of this down= ward flow, around the piston 1, in preventing contami= nation of liquid 3 by liquid or slurry 4, and the degreeof dilution of liquid or slurry 4 by liquid 3 are con= trollable, and are proportional to the specific weights of liquid 3, and the piston, and to the annular area be= tween the piston and displacement cylinder walls in the horizontal diametral plane of the piston.

The cycle of operation for the transfer of pressure energy between liquid 3 and liquid or slurry 4 will be considered in detail commencing with the piston 1 descending in the displacement cylinder 2, and at a posltion intermediate between the upper and lower limitmg positions 40 and 41 respectively.

During the descending stroke of the piston 1 liquid 3 at high pressure energy is continuously admitted to the upper cylinder cover opening 8 maintaining the specific energy of liquid 3, over the piston, above that of liquid or slurry 4 at entry and discharge valve outlets 20 and 21 respectively. Liquid or slurry 4 is expelled from the lower cylinder cover outlet 10 and flows, via piping 11, between valve 17 and valve seat 19 to discharge from outlet 21. The pressure gradient across entry valve 16 maintains sealing contact between this valve and valve seat 18. The descending stroke of the piston 1 continues until the lower limiting position 41 is reached when the supply of high pressure energy liquid 3 to the upper cylinder cover entry 8 ceases. The specific energy of liquid 3, above the piston, is correspondingly reduced below that of liquid or slurry 4 at the entry and discharge valve unit outlets 20 and 21 respectively, thus causing discharge valve 17 to close and make sealing contact with valve seat 19, and terminating the flow of liquid or slurry 4 from the displacement cylinder 2. Simultaneously entry valve 16 breaks contact with valve seat 18 allowing liquid or slurry 4 to flow through the entry valve unit 12, from feed opening 20, to enter the lower cylinder cover entry 10, via piping 11, displacing piston 1 vertically u wards, and expelling low pressure energy liquid 3 from the upper cylinder cover entry 8.

The ascending stroke of the piston continues until it reaches the upper limiting position 40, and makes contact with the internal surface of the upper cylinder cover 5 and seal 7, as shown in FIG. 4. The difference in pressure energy of liquid 3 and liquid or slurry 4 establishes a pressure gradient over the seal 7 forming a fluid tight barrier between the piston 1 and upper cylinder cover 5, and preventing reversal of the normal liquid flow pattern around the piston, shown by arrows 42, which would result in contamination of liquid 3 by liquid or slurry 4.

Following a further small increment of time liquid 3 of high pressure energy is admitted to the upper cylinder cover opening 8 breaking the .seal between piston 1 and upper cylinder cover 5, and increasing the specific energy of liquid 3, over the piston 1 above that of liquid or slurry 4 at feed and discharge openings, 20 and 21 respectively. The subsequent pressure gradients over entry and discharge valves, and 17 respectively, operate instantaneously to close entry valve 16 on valve seat 18, and breaks contact between discharge valve 17 and valve seat 19 allowing high pressure energy liquid or slurry 4 to flow from the displacement cylinder 2, via piping 11 and discharge valve unit 13, to the discharge outlet 21, as the piston descends to repeat the cycle.

In the means of performing the invention as depicted in FIG. 1, admission of high pressure energy liquid 3 to, and expulsion of low pressure energy liquid 3 from the upper cylinder cover 5 is controlled by the timing valve unit 22. Under the control of the drive unit 23, the timing valve unit 22 alternately communicates high pressure entry and low pressure outlet connections, 24 and 25 respectively, with the interior of said timing valve unit, and thence with the upper cylinder cover entry 8. Liquid 3, in a state of high pressure energy, is thus alternately admitted from the multi stage centrifugal pump 28 to the upper cylinder cover 5, and discharged therefrom, in a state of low pressure energy, to the pump feed reservoir 29. Fluctuation in delivery flowrate may be minimised by the operation of a number of pumping mechanisms, comprising timing valve units 22, displacement cylinder assemblies 9, and entry and discharge valve units 12 and 13 respectively, in parallel, to be energised by a common pump 28, and having discharge outlets 21 connected to a common discharge pipeline. Timing valve units 22 would be mechanically coupled together with constant phase displacements, and driven by a common drive unit 23.

In the means of performing the invention as depicted in FIG. 2, admission of high pressure energy liquid 3 to, and expulsion of low pressure energy liquid 3 from the upper cylinder cover 5 is directly controlled by the motion of the piston 33 in the reciprocating pump 34, and the rate of admission or expulsion of liquid 3 respectively to and from the upper cylinder cover 5 at any instant is directly proportional to the lineal velocity of said piston in the cylinder 32 at that instant. Check valve 36 provides for entry of additional liquid 3 from a reservoir 39 to compensate for liquid lost by contamination or dilution, of liquid or slurry 4, and maintains substantially constant volume of liquid 3 in the circuit.

Fluctuation of flowrate may be minimised by operating a number of pumping mechanisms, including reciprocating pumps 34, displacement cylinder assemblies 9, and

entry and discharge valve units 12 and 13 respectively, in parallel, and having discharge outlets 21 connected to a common discharge pipeline. Fluctuation of delivery flowrate may be minimised by mechanically coupling reciprocating pumps 34 together with constant phase displacements.

What I claim-is:

1. A liquid displacement pressure transfer pump comprising a vessel having a first and a second liquid medium therein with the first liquid medium superposed above the second liquid medium, said second liquid medium having a greater specific weight than first liquid medium, and a separator member of a bulk specific Weight not greater than the specific weight of said first liquid medium floating and moving freeing adjacent and With the transition zone between said first and second liquid media, said separator member conforming to the walls of said vessel and having a working clearance therewith, said vessel having valved connections, Whereby in cyclic operation said first liquid medium is admitted to said vessel at a pressure dilferent from that of said second liquid medium to thereby displace said second liquid medium from said vessel by pressure transfer form and through said separator member, whereafter said second liquid medium is admitted to said vessel at a pressure difierent from that of said first liquid medium to thereby displace said first liquid medium from said vessel by pressure transfer from and through said separator member.

2. A liquid displacement pressure transfer pump as claimed in claim 1 in which said separator member is a spherical member.

3. A liquid displacement pressure transfer pump as claimed in claim 1, wherein the clearance area between said separator member and the Walls of said vessel is proportioned with respect to the relative specific weights of said separator member and said first liquid medium to cause said separator member to rise relative to said first liquid medium at a predetermined rate.

4. A liquid displacement pressure transfer pump as claimed in claim 2, wherein the clearance area between said separator member and the walls of said vessel is proportioned With respect to the relative specific weights of said separator member and said first liquid medium to cause said separator member to rise relative to said first liquid medium at a predetermined rate.

References Cited by the Examiner UNITED STATES PATENTS 125,410 4/1872 Riker 103-52 X 2,478,051 8/1949 Nordell 230-105 2,644,401 7/1953 Ragland 103-52 X FOREIGN PATENTS 1,297,637 10/ 1961 France.

ROBERT M. WALKER, Primary Examiner.

Claims (1)

1. A LIQUID DISPLACEMENT PRESSURE TRANSFER PUMP COMPRISING A VESSEL HAVING A FIRST AND A SECOND LIQUID MEDIUM THEREIN WITH THE FIRST LIQUID MEDIUM SUPERPOSED ABOVE THE SECOND LIQUID MEDIUM, SAID SECOND LIQUID MEDIUM HAVING A GREATER SPECIFIC WEIGHT THAN FIRST LIQUID MEDIUM, AND A SEPARATOR MEMBER OF A BULK SPECIFIC WEIGHT NOT GREATER THAN THE SPECIFIC WEIGHT OF SAID FIRST LIQUID MEDIUM FLOATING AND MOVING FREEING ADJACENT AND WITH THE TRANSITION ZONE BETWEEN SAID FIRST AND SECOND LIQUID MEDIA, SAID SEPARATOR MEMBER CONFORMING TO THE WALLS OF SAID VESSEL AND HAVING A WORKING CLEARANCE THEREWITH, SAID VESSEL HAVING VALVED CONNECTIONS, WHEREBY IN CYCLIC OPERATION SAID FIRST LIQUID MEDIUM IS ADMITTED TO SAID VESSEL AT A PRESSURE DIFFERENT FROM THAT OF SAID SECOND LIQUID MEDIUM TO THEREBY DISPLACE SAID SECOND LIQUID MEDIUM FROM SAID VESSEL BY PRESSURE TRANSFER FORM AND THROUGH SAID SEPARATOR MEMBER, WHEREAFTER SAID SECOND LIQUID MEDIUM IS ADMITTED TO SAID VESSEL AT A PRESSURE DIFFERENT FROM THAT OF SAID FIRST LIQUID MEDIUM

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