US1902729A

US1902729A - Multistage liquid driven ejector for delivering liquids

Info

Publication number: US1902729A
Application number: US628247A
Authority: US
Inventors: Schmidt Paul
Original assignee: Individual
Current assignee: Individual
Priority date: 1931-08-15
Filing date: 1932-08-10
Publication date: 1933-03-21
Anticipated expiration: 1950-03-21

Description

' Patented Mar. 21, 1933 UNITED STATES PAUL SCHMIDT, OI MUNICH, GERMANY IULTISTAGE LIQUID DRIVEN EJ'ECTOR FOR DELIVERING LIQUIDS Application filed August 10, 1932, Serial No. 628,247, and in Germany August 1}}, I931.

' In addition to the well known ways of deliverin liquids by means of reciprocating or centri ugal' pumps, a number of methods of delivery have become known, the use of which, in special cases, afl'ords special advanta es. Among these different methods of de ivery, some use has been made of deliveriyl by the so-called Mammut pumps (in whic air or gas is introduced at the lower end of the immersed delivery pipe for the purpose of forming a mixture of gas and liquid in the delivery pipe) and also of methods employing steam injectors, hydraulic rams and uniformly acting liquid ejectors.

The present invention relates to a particularly advantageous embodiment of this last named device, that is to say, of the uniformly acting, liquid driven e ector for the delivery of liquids. The embodiment according to the present invention ensures the delivery of liquids by ejector action even to the greatest delivery heights occurring in practice, whereas, as is well known, it has not hitherto been possible to overcome very great delivery heights (many hundreds of metres for example) by ejectors. It is true that the literature on the subject contains certain suggestions for the construction and use of ejectors for these purposes, (among others, the suggestion to use a multi-stage arrangement) but none of these suggestions could be successfully carried out in practice.

The difficulties attending the practical working of ejectors of this kind will now be demonstrated with reference to the graphs shown in Figs. 1, 2 and 3 of the accompanying drawing, Fig. 4 of which shows diagrammatica I a two-stage ejector constructed according to the present invention.

Fig. 1 shows, for comparison with the ejector according to the present invention, the output curve H of a single stage ejector of the normal construction such as has been quite usual heretofore. The correspondin efliciencies at various outputs are denote by the curve n.

Thus curve H shows the height of delivery for various different quantities of liquid raised, while the curve n gives the corresponding degrees of efliciency for the various .be observed that both these curves follow PATENT OFFICE- quantities and at the various delivery heights plotted in curve H. This customary method of representing the output of an ejector shows fully and exactly how the apparatus behaves under working conditions.

In Fig. 1 the curve H extends only over a range of comparatively low delivery heights and comparatively large volumes of liquid delivered. At these outputs, which have been customary heretofore with uniformly acting ejectors, relatively high efliciencies have been obtained and no difliculties have been experienced in practical working.

N ow Fig. 2 shows the output curve of an ejector for very great heights of delivery, amounting to many hundreds of metres. Here, again, the output curve (height of .delivery plotted against quantity of liquid de-v livered) is denoted by H and the corresponding efiiciency curve by n, as in Fig. 1. It will courses very different from those of the H I and n curves for a normal ejector (Fig. 1). Thus in the course of a large number of experiments, it has been found that ejectors of this kind, which are desi ed to deliver relatively small quantitieso liquid to very great heights, in man cases give no normal output curve at all. n the contrary even at the smallest delivery the action of the driv- 8o ing jet suddenly ceases,'so that this value of the delivery cannot be exceeded without further aid. In the output curve shown in Fig. 2 this point is denoted by 1. It should be noted that the output curve breaks off even befone the ejector has reached its normal output. j According to the measurements made of ejectors which have actually been constructed, this falling off, or breakdown must be attributed to a deviation from the normal pressure at the entrance to the diffuser of the ejector. At this region there is set up apartial vacuum which tends to draw the current of liquid away from the walls and naturally this results in a corresponding restriction of the free cross sectional area and throttles 011' any further su ply ofliquid.

It has now en found that by the provision of two or more stages of a peculiar construction the disadvantage illustrated by the curves. in Fi 2 can be obviated. Accordingly, the su ject matter of this invention is a multi-stage liquid driven ejector for the deliver of liquids, particularly of rock oil from eep bore holes, the feature of which is that, in the first stage, the magnitude of the exit cross sectional area of the driving nozzle is less than 0.5 of the size of the smallest cross sectional area of the difiuser, and that in the second stage, the size of the exit cross sectional area of the driving nozzle is more than 0.6 of the size of the smallest cross sectional area of the difi'user. A multi-stage ejector according to the invention may comprise two or more stages.

The advantageous action of these multistage ejectors, according to the invention, is shown by the curves given in Fig. 3, in which,

, as in Figs. 1 and 2, the output curve is denoted by H while the corresponding efliciencies are shown by,the curve n.

This Figure 3 shows the H and n values obtainable with a twostage ejector, constructed according to this invention and operating to deliver very small quantities of liquidto very great heights (as previously attempted with the single-stage pump the curves of which are given in Fig. 2 Now, on comparing Fig. 3 with Fig. 2, it can be seen that, by arranging the cross sectional areas of the jet nozzles and difi'users according to the present invention the curve of delivery height H and the efiiciency curve-can be made to assume a normal course somewhat similar to that obtained with an ordinary ejector (c. f. Fig. 1). The important difference, however, between the ejector to which Fig. 1 applies, and the ejector according to this invention is that the new construction makes it possible to reach hitherto unattainable heights of delivery with relatively very small quantities of liquid delivered. In apparatus according to the invention the output from the first stage is very small per se, so that this first stage forms, as it were, only preliminary stage to. the

. second or main stage, which supplies by far the greater part of the total output.

By the interpolation of the first stage the liquid to be delivered is supplied to the second or main stage at a certain initial -pressure. In this way the formation of cavities or the separation of the liquid stream from the walls at the'entrance to the .difiuser is effectively avoided, so that a normal output the relationship.

nozzle is denoted by 4. The jet of liquid from the nozzle 3 flows into the diffuser 5, the smallest cross sectional area of which is denoted by 6. The exit cross sectional area 4 of the driving nozzle 3 is less than 0.5 of .the smallest cross sectional area of the diffuser 5, as denoted by 6. The delivered liquid issues from the difiuser 5 together with the driving liquid delivered through the nozzle 3, both passing upwards to the second stage of the ejector. The driving nozzle of the second stage is denoted by. 7 and the exit cross sectional area of this driving nozzle 7 is indicated b 8. The liquid issuing from the nozzle 7 ows, together with the liquid delivered from the first stage into the diffuser 9 of the second stage." The smallest cross sectional area of this diffuser 9 is indicated by 10. The exit cross sectional area 8 of the nozzle 7 is, according to this invention, more than 0.6 of the smallest cross sec- ?)ional area of the diffuser 9, as indicated It will be seen from the action of the two stages arranged in series that in all cases the second stage must be placed comparativelv close to the'first stage and, in general, the first two stages of any ejector according to this invention must be placed conjointly at the beginning of a delivery pipe.

Having now particularly described and ascertained the nature of my said invention and in what manner the sameis to be per- 7 size of the-exit cross sectional area of the drlving nozzle is more than 0.6 oftlfe size of the smallest cross sectional area of the diffuser.

In testimony whereof I have signed my name to this specification.

' PAUL SCHMIDT.