US2939404A

US2939404A - Liquid transfer

Info

Publication number: US2939404A
Application number: US386635A
Authority: US
Inventors: Clarence J Schilling
Original assignee: Air Products Inc
Current assignee: Air Products Inc
Priority date: 1951-12-18
Filing date: 1953-09-22
Publication date: 1960-06-07
Anticipated expiration: 1977-06-07

Description

June 7, 1960 c. J. SCHILLING LIQUID TRANSFER Original Fil'ed Dec. 18, 1951 2 Sheets-Sheet;

3 32 INVENTOR.

June 7, 1960 c. J; SCHILLING LIQUID TRANSFER Original Filed Dec. 18, 1951 2 Sheets-Sheet 2 INVENTOR. are zce $56k iZ i gf,

States LIQUID TRANSFER Clarence J. Schilling, Allentown, Pa., assignor to Air Products Incorporated, a corporation of Michigan 7 Claims. (Cl. 103-232) This is a divisional application of application Serial No. 262,235 filed Dec. 18, 1951, now abandoned.

This invention relates to improvements in liquid transferring devices and more particularly to methods of and apparatus for elevating liquids responsively to pressure differentials produced through density changes.

It is well known that liquids may be elevated by changing their effective density upon the introduction or addition of a fluid of less density thereto, such as the introduction of compressed air into the e'duction column of the conventional air lift. Air lifts and other fluid lift pumps functioning on this principal of aeration offer certain advantages over mechancal pumps which depend upon the action of pistons, plungers or impellers to move the liquid material. However,.theefliciency of the prior fluid lift pumps is low as compared to mechanical pumping 'devices except for special environments and their use may be impracticable from art economic viewpoint unless an adequate source of low cost fluid pressure is available for aeration. Also, when it is desired totransfer liquid material to a relatively high elevation, a large number of fluid lift pumps are required to be connected in series relation due to their low lift per stage. For these reasons, their'use may be prohibited by the available space and the initial cost as well as by the operating expense. Moreover, since the prior devices function by introducing fluid under pressure into the liquid, they possess very little if any utility in instances where the introduction of a foreign fluid would produce undesirable results, such as where the fluid would contaminate the liquid or produce physical orchemical changes therein. Thus, employment of air lifts and similar prior art devices are restricted to those limited situations wherein special circumstances exist.

It is therefore an' object of the present invention to provide a novel method of and means for lifting liquid material by means of density variations which overcomes the disadvantages and limitations inherent in the prior methods and devices.

Another object of the present invention is to provide a method and apparatus for lifting liquids responsively to density variations wherein the density variations are produced without introducing foreign substances to the liquid.

Another object of the present invention is to provide a method and apparatus for lifting liquids which are under temperature and pressure conditions at or near their boiling points merely by the addition of heat.

Another object is to provide amethod and apparatus of the foregoing character wherein the density variations are produced substantially independently of liquid head.

Still another object is'to provide a novel liquid lifting methodand apparatus including a plurality of lift stages connected in cascade relation to produce a total lift for a'given number of stages, greatly in excess of the total lift obtainable by a corresponding number of stages in the prior lift pumps.

Still another objectis'to provide a' liquid'lifting apparatus of the foregoing character wherein the lift per ice.

stage increases according to a substantially geometric function.

Other objects and features of the present invention will appear more fully hereinafter from the following detailed description consideredin connection with the accompanying drawings. It is understood however that the drawings are designed for purposes of illustration only and not as a definition of the limits of the invention, reference for the latter purpose being bad to the appended claims.

- In the drawings, wherein similar reference characters denote similar elements throughout the several views:

Fig. 1 is a diagrammatic view of a liquid lift pump cycle constructed in accordance with the principles of the present invention, and

' Fig. 2 is a diagrammatic view of another form of liquid lift pump cycle illustrating the present invention.

According to the present invention, aeration of liquid material in the eduction or uplift section of a liquid lift pump is obtained by changing a portion of the material from liquid to gaseous phase, thus producing a liquid and gaseous mixture of the material having a density less than the density of the material in liquid phase alone, that is, of adensity less than the density of the submergencehead. This phase change, or partial vaporization, may be accomplished by passing a suitable heat conducting medium,

' at the proper temperature, in heat interchange with the liquid in-the eduction or uplift sections. The present invention also employs this type of aerating means in a liquid lift pump including serially connected eduction I conduits extending upwardly from a common elevation to provideacascade liquid lift pump producing a lift per stage that increases in accordance with a substantially geometric function. According to a modification of the invention, the-pressure differential between the submergence and'eduction heads may be further increased by refrigerating the liquid material in the submergence conduits or sections. I

With reference more particularly to Fig. l of the drawings; a cascade liquid lift pump constructed in accordance with one. embodiment of the invention is disclosed for lifting liquid material in a reservoir 10 to a receiver 11 located at a higher elevation. It is understood that the reservoir and the receiver are respectively representative of any source of liquid and a related higher elevation receiving point, such as the liquid in a subterranean well and a receiving tank mounted on thesurface of the earth. The lift pump includes a plurality of eduction or uplift columns or uptake conduits or sections 12, 13 and 14 successively positioned between the reservoir and the receiver. The lower ends of the uplift columns include inlet portions 15, 16 ,and 17, respectively located at a substantially common elevational level, while their upper ends are terminated in respective discharge portions 18, 19 and 20 at successively higher elevations between the reservoir and the receiver. A submergencesection or column is provided for each of the uplift columns, and each uplift column with its submergence section comprises one lift stage of the pump. A conduit 21 transfers liquid from the reservoir 10 to the inlet portion 15 of the uplift column 12, and thus the reservoir liquid constitutes the submergence head for the first stage. Of course, it is understood that the first stage may be fed by inserting the lower end of the uplift col umn 12 directly into the reservoir liquid. The submergence section for the second stage comprises a conduit 22 connected between the discharge portion 18 of the first stage and the inlet portion 16 of the uplift conduit 13, while a conduit 23, connected between the discharge portions 19 of the second stage and the inlet portion 17 of the uplift column 14, constitutes thesubmergence section for the third stage.

As mentioned above, one of the objects of the present invention is to provide a novel method and means for aerating the liquid in the eduction or uplift columns, without introducing, mixing or otherwise bringing foreign substances into contact with the liquid material to be pumped. This object is accomplished by adding heat to the liquid within the uplift columns to bring about a phase change and convert a small percentage of the material from liquid to gaseous phase. Inasmuchas the density of a substance in gaseous phaseis under most conditions, extremely less than its density in liquid phase, the partial vaporization produces a liquid and gaseous mixture having a density substantially less than ,the density of the substance in liquid phase alone. Forexample, in the neighborhood of atmospheric pressure the density of a volume .of a mixture of 99% liquid oxygen and 1% gaseous oxygen is approximately four times less than the density of an equal volume of 100% oxygen in liquid phase. Thus, in such case a theoretical ratio of lift to submergcnce head of approximately 4 to 1 can be obtained by vaporizing only 1% of a volume of liquid oxygen. The partial vaporization of the liquid material may be obtained by controllably applying heat'to the liquid in the uplift columns. complishing this heating function may include a heat exchanger associated with each of the uplift columns. As shown in Fig. 1 hollow

cylindrical heating jackets

24, 25 and 26 are provided for the uplift columns 12, 13 and 14, respectively. Each of the heating jackets surrounds its uplift column and extends upwardly a substantial distance from the lower end. An input conduit 27 and an output conduit 28 are provided with connections with each of the heating jackets for circulating a heat conductin-g medium or fluid in heat exchange relationwith the uplift columns.

Valves

29, 30 and 31 may be provided in the portions of the conduit 27 feeding the

heating jackets

24, 25 and 26, respectively, for controlling the quantity of heat added to respective uplift columns. A heat interchanger 32, shown in the form of a cylindrical heating jacket having an input conduit 33 and output conduit 34 is positioned about conduit 21 for passing a warm fluid in heat exchange with the liquid feeding the first stage of the pump. This heat interchanger functions as a preheater and may be utilized in instances when the reservoir liquid is at a temperature substantially below its boiling point temperature.

Vapor collecting conduits

35, 36 and 37 are provided extending from the discharge portions 18, 19 and 20 of the uplift columns. The vapor collecting conduits lead to a common manifold 38 for collecting the vapors generated during operation of the pump. .Inasmuch as the pumping force is produced upon introduction of heat energy to the system, it may be necessary in some instances, and preferable in others, to fully insulate the liquid conducting portions of the pump to prevent heat transfer.

In operation, liquid from the reservoir flows through the conduit 21 and upwardly into the uplift conduit 12 to a level corresponding to the liquid level in the reservoir. When a controlled amount of heat is applied to the uplift conduit 12, through the conduit 27 and heating jacket 24, a small percentage of the liquid is changed into gaseous phase, thus forming a liquid and gaseous mixture within the uplift conduit having a density less than the density of the liquid in the reservoir 10. The heavier reservoir liquid, acting through the submergence head S forces the liquid and gaseous mixture upwardly in the column 12 and into the discharge portion 18. The liquid level of the mixture is raised through a height L above the surface of reservoir liquid, and this comprises the lift produced by the first stage. The unitary ratio of lift to submergence head disclosed for this stage, as well as for the other stages, is merely illustrative inasmuch as greater ratios may be readily obtained as discussed above. The vapor emerging from the first stage flows into conduit 35 and collects in the One arrangement for ac-' manifold 38 while the liquid discharges into the submergence conduit 22 of the second stage, eventually filling the uplift column 13 as well as the submergence conduit 22 to an elevation corresponding to the maximum liquid level of the first stage. Upon partial vaporization of the liquid within the uplift conduit 13, upon application of heat through the heating jacket 25, the heavier submergence head S forces the liquid and gaseous mixture upwardly in the uplift column :13 and from the discharge portion 19 at a lift elevation L A similar operation takes placein the third stage wherein the submergence head 8; provides the force for lifting the lighter liquid and gaseous mixture in the uplift column 14 through the lift elevation L After the pump has started up, a continuous stream of liquid from the reservoir 10 flows into the uplift column 12, successively through the submergence and uplift conduits of the second and third stages and is discharged into the receiver 11. The heat conducting medium supplied by the conduit 27 flows continuously through the cooling

jackets

24, 25 and 26 to supply substantially the same quantity of heat and hence to produce substantially the same degree of vaporization in each of the lift stages. Of course, when the liquid to be pumpedis at its boiling point temperature a minimum quantity of heat is required, and when-its temperature is substantially :removed from the boiling point temperature at the existing pressure a proportionately greater quantity of heat must be supplied to provide the vaporization. It is preferable to supply this additional heat by employing the heat interchanger 32 to preheat the liquid to its boiling point temperature before its entry into the first stage.

Themethod ofaerating the liquid by changing a portion of the material from liquid phase to gaseous phase upon .the application of externalheat, widely increases the utility of liquid lift pumps inasmuch as the problems of liquid contamination and chemical affiliation due to the use of pressurized fluid for aeration are not present. Also, aeration by vaporization produces bubbles of minute dimensions which cannot be attained by mechanical foot pieces used with fluid pressure aerating arrangements and thus reduces slippage losses to a minimum and provides an over-all increase in efiiciency.

It is well known in the art of liquid lift pumps that the lift produced is a function of the submergence head, and that the lift increases as the submergence head is made larger. However, in conventional liquid lift pumps employing fluid pressure to produce the aeration, a rise in submergence head requires an increase in the pressure of the aerating fluid, and in most installations, the submergence head, and consequently the lift, is limited by the fluid pressure available for aeration. This limitation is not present when practicing the present invention using heat inasmuch as the heat may be added to the fiquild substantially independently of the submergence This feature of the present invention has application in cascade lift pumps and lends to a practical formation of an ideal cascade lift pump wherein the lift per stage increases according to a substantially geometric function. This type of lift pump is illustrated in'Fig. 1 wherein the uplift conduits 12, 13 and 14 are extended downwardly with theirinput portions 15, 16 and 17 lying in a substantially common plane, which in the ideal situation, comprises the lowest liquid point in the system,-such as the bottom of a subterranean well. With this arrange ment, the submergence head for each stage, excluding the first stage, equals thecombined submergence head and lift of the preceding stage. As illustrated, the submergence head S equals the sum of the submergence head S and the lift L while the submergence head S equals the combined submergence head 8;; and lift L Thus the lift per stage disproportionately" increases through thecascade relation approximating a geometric function. Although the eduction conduits are of unassess;

equal height'substantially the same quantity of heat may be applied to the

heating jackets

24, 25 and '26 since, after starting up, an equal quantity of liquid flows through the uplift and submergence conduits requiring substantially the same degree and rate of vaporization in each of the uplift conduits. Under actual operating conditions heat transfer may occur in the'system especially in the unheated portions of the uplift conduits. The heat transfer may result in condensation of vapor bubbles or excessive vaporization of the liquid material. Ordinary heat transfer may be sufiiciently minimized by adequate insulation not to interfere with normal operation of the pump. Otherwise it may be compensated for by controlling the heat applied to the uplift conduits. Also, where the unequal liquid heads in the uplift columns appreciably affects the boiling point of the liquid at the lower ends of the columns, measurable quantities of additional heat may be supplied to bring about the required amount of vaporization,

Valves

29, 30 and 31 may be employed for this purpose.

The form of invention illustrated in Fig. '2 includes the features of the liquid lift pump describedabove and provides additional means for increasing the lift per stage. This means comprises an arrangement for removing heat from the liquid in the submergence sections to thus increase its density and hence the pressure differential between the eduction and submergence heads. This feature has particular utility in instances where sufficient lift cannot be obtained by vaporization alone and ample heat is available to provide the additional term perature rise for vaporization. The arrangement includes cooling

jackets

40 and 41 positioned around the submergence conduits 212 and 23 respectively, and a cooling coil 42 positioned in the reservoir 10. A cooled fluid supplied by a refrigerating apparatus, not shown, is conducted through the cooling

jackets

40 and 41 and the coil 42 by way of input conduit 43 and output conduit 44.

Operation of this form of the invention is similar to operation of the Fig. 1 arrangement described above with the exception that the heat removed from the submergence sections increases the density of the liquid, and hence the submergence head, thus producing a greater lift per stage. The methods and apparatus of Figs. 1 and 2 are applicable to any field of use but especially those fields in which a liquid to be lifted is at or near it boiling point. These applications range from high temperature systems including high boiling point liquids through atmospheric temperature systems where low boiling point liquids are involved and to low temperature systems where difficultly liquefiable gases are being handled in liquid phase. There is provided by the present invention a novel method of and apparatus for lifting liquids from a reservoir at a low elevation to a receiver at a higher elevation. Liquid lift pumps embodying the principles of the present invention are capable of lifting practically all types of liquids, such as liquefied petroleum gases, gasolene and other liquid hydrocarbons and liquefied oxygen and nitrogen. Also, practically all types of liquid chemicals can be lifted with the present pump which ordinarily are difl'icult to handle by mechanical pumping means or by conventional air lift types of pumps due to chemical affiliation with pumping components or because of purity requirements. Also, liquid lift pumps embodying the principles of the present invention do not include limiting characteristics as found in the prior art and provide for utilization of maximum submergence heads and the formation of cascade liquid pumps wherein the lift per stage varies according to a substantially geometric function and wherein the total lift obtained from a given number of stages by far exceeds the lift produced by a conventional lift pumpemploying a similar number of stages.

Although a number of features and different modifications of the present invention have been disclosed and described herein, it is expressly understood that Variouii changes and substitutions may be made therein without departing from the spirit of the invention as well under stood by those skilled in the art. For example, while the liquid lift pump is shown as including three stages connected in cascade relation, it is understood that the novel methods and apparatus provided herein have application'to a lift pump including one stage or to a cascade lift pump including a greater number of stages, while the ratio of lift per submergence head as well as the lift per stage are disclosed for the purposes of illustration only. Reference therefore will be had to the appended claims fora definition of the limits of the invention.

What is claimed is:

1. A liquid lift pump comprising a succession of alternately disposed "uplift and submergence liquid convey: ing conduits connected in series with the upper. end of one uplift conduit being connected to the upper end of the next submergence conduit of the succession and with the lower end of the latter submergence conduit being connected to the lower end of the next uplift conduit of the succession to form a closed path for the flow of liquid material through the succession, the length of the sub: mergence conduits increasing progressively. along the succession and the upper endsof the upliftconduits being at different elevations with the difference in elevation between the upper ends of the uplift conduits increasing progressively along the succession, means for partially vaporizing liquid material fedtothe uplift conduits and means at the upper ends of the upliftconduits for removing vapor from the closed path.

2. A liquid lift pump comprising a succession of alternately disposed uplift and submergence liquid convey ing conduits connected in series with the upper end of one uplift conduit being connected to the upper end of the next submergence conduit of the succession and with the lowerend of-the latter submergence conduitbeing connected to the lower end of the next uplift conduit of the succession, the length of the submergence conduits increasing progressively along the succession and the upper ends of the uplift conduits being at different elevations with the difference in elevation between the upper ends of the uplift conduits increasing progressively along the succession, means for partially vaporizing liquid material fed to the uplift conduits, and means for increasing the density of liquid material in the submergence conduits.

3. A liquid lift pump comprising a succession of alternately disposed uplift and submergence liquid conveying conduits connected in series with the upper end of one uplift conduit being connected to the upper 'end of the next submergence conduit of the succession and with the lower end of the latter submergence conduit being connected to the lower end of the next uplift conduit of the succession, the length of the submergence conduits increasing progressively along the succession and the upper ends of the uplift conduits being at different elevations with the difference in elevation between the upper ends of the uplift conduits increasing progressively along the succession, and means forming a liquid and gaseous mixture in the uplift conduits having a density less than the density of liquid material in the submergence conduits, the last-named means including means for partially vaporizing liquid material fed to the upliftconduits, and means for removing vapor from liquid in. the submergence conduits.

4. A liquid lift pump comprising a succession of alternately disposed uplift and submergence liquid conveying conduits connected in series with the upper end of one uplift conduit being connected to the upper end of the next submergence conduit of the succession and with the lower end of the latter submergence conduit being connected to the lower end of the next uplift conduit of the succession, the length of the submergence conduits increasing progressively along the succession and the upper ends of the uplift conduits being at different elevations with the difference in elevation between the upper ends of the uplift conduits increasing progressively along the "succession, heat exchange means for the uplift conduits, and means for passing relatively warm fluid to the heat exchange means.

5. A liquid lift pump comprising a succession of alternately disposed uplift and submergence liquid conveying conduits connected in series with the upper end of one uplift conduit being connected to the upper end of' the next submergence conduit of the succession and with the lower end of the latter submergence conduit being connected to the lower end of the next uplift conduit of the succession, the length of the submergence conduits increasing progressively along the succession and the upper ends of the uplift conduits being at different elevations with the difference in elevation between the upper ends of the uplift conduits increasing progressively along the succession, first heat exchange means for the uplift conduits, second heat exchange means for the submergence conduits, means passing relatively Warm fluid to the first heat exchange means, and means passing relatively cold fluid to the second heat exchange means.

6. A device for transferring liquid material from a source at a low elevation to a relatively high elevation comprising a succession of alternately disposed uplift and submergence liquid conveying conduits connected in series with the'upper end of one upliftconduit being connected to the upper end of the next submergence conduit of the succession and with the lower end of the latter submergence conduit being connected to the lower end of the next uplift conduit of the succession, the lower ends of the submergence conduits being at an elevation at least as low as the low elevation of the source and the length of the submergence conduits increasing progressively along the succession, the upper ends of the uplift conduits being at different elevations with the difference in elevation between the upper ends of the uplift conduits increasing progressively along the succession, and means L! for reducing the density of liquid material in the uplift conduits, the last-named means including heat exchange means in heat exchange relationship with at least the lower portion of the uplift conduits and means for passing relatively warm fluid through the heat exchange means.

7. A device for transferring liquid material from a source at a low elevation to a relatively high elevation comprising a succession of alternately disposed uplift and submergence liquid conveying conduits connected in series, conduit means connecting the source to the lower end of the first uplift conduit of the succession, the upper ends of the uplift conduits except the last uplift conduit of'the succession being connected to the upper end of the next respective submergence conduit of the succession and the lower ends of the submergence conduits being connected to the lower end of the next respective uplift conduit of the succession, the length of the submergence conduits increasing progressively along the succession and the upper ends of the uplift conduits being at different elevations with the difference in elevation between the upper ends of the uplift conduits increasing progressively along the succession, means for warming liquid flowing through the conduit means to its boiling point temperature at the existing pressure, and means for partially vaporizing liquid material in the uplift conduits.

References Cited in the file of this patent UNITED STATES PATENTS 1,071,878 Chodzko Sept. 2, 1913 1,537,264 Rogers May 12, 1925 1,798,946 Maiuri et al. Mar. 31, 1931 2,116,191 De Baufre May 3, 1938 2,240,925 De Baufre May 6, 1941 FOREIGN PATENTS 24,024 Great Britain of 1899