US3922112A

US3922112A - Eductor jet pump and method

Info

Publication number: US3922112A
Application number: US454127A
Authority: US
Inventors: John A Miscovich
Original assignee: Marcona Corp
Current assignee: Marcona Corp
Priority date: 1973-09-20
Filing date: 1974-03-25
Publication date: 1975-11-25
Anticipated expiration: 1992-11-25

Abstract

An eductor jet pump including a venturi throat mounted at the input end of a discharge line into which a high velocity fluid jet nozzle is directed. Hydraulic cylinders and a hydraulic control circuit provide for relative movement of the jet nozzle toward or away from the venturi throat for either pulsating operation by regular cycling of the nozzle portion, for specific control of efficiency by nozzle position, or for closing the venturi throat to prevent backflow.

Description

United States Patent Miscovich 1 Nov. 25, 1975 [SH EDUCTOR JET PUMP AND METHOD 1,671.564 5/1928 Andrewsuwhn ,417/184 1 John Mismvich- Orangev liiiiill 111323 iiihiliiji'iii;;1'" $311123 [73] Assignee: Marcona Corporation, S 3.389938 6/1968 Fnizierm. U KHZ/14 Francisco, Calif Primarv E.taminerCarlton R. Crovhe [22] Flcd Mar. 1974 Assistant Examiner-Richard E. (iluck [2i] Appl. No: 454,127 Attorney, Agent, or FirmFlehr. Hohhach, Test,

Related US. Application Data Albrmon & Herbert [60] Division of Ser, Nov 398,98l, Sept. 20, 1973. Pat,

No. 1816027. which is a continuation of Ser, No. [57] ABSTRACT 181.017, Sept. l6 1971, abandoned,

An eductor jet pump including it vcnturi throat [52 US CL 417/54 mounted at the input end of at discharge line into [51] z n F04}; 5/48 which a high velocity fluid jet nozzle is directed Hy- [5 Field of Search 4l7/54 \83 190 draulic cylinders and ti hydraulic control circuit prog o; 302/14 15 42 vide for relative movement of the jet nozzle toward or away from the venturi throat for either pulsating oper [56] References Cited ation by regular cycling of the nozzle portion. for spe- UNITED STATES PATENTS cific control of efficiency by nozzle position. or for closing the venturi throat to prevent buckllow, 1.133.601 3/1915 Wood il H183 4 Claims, 4 Drawing Figures g T: r" A 16 -2- 2;

l7 1 t ELASTOMERIC f; LINING LlNlNG U.S. Patent Nov. 25, 1975 Sheet 2 of2 3,922,112

Fla--4 EDUCTOR JET PUMP AND METHOD CROSS-REFERENCE TO RELATED APPLICATIONS This application is a division of applications Ser. No. 398,98], filed Sept. 20, 1973, which is a continuation of application Ser. No. 18l,0l7, filed Sept. 16, l97l and now abandoned. The application Ser. No. 398,98l was issued on June ll, I974 as US. Pat. No. 3,816,027.

This invention relates to eductor jet pumps and to methods of their operation in which a high velocity fluid is passed through a venturi throat to create a lifting force for material in the vicinity of the throat opening. In one particular application, the eductor jet pump finds application for use in the dewatering of settled slurries over a wide range of elevations such as is encountered in the progressive loading and dewatering of supernatant liquids from settled mineral ore slurries aboard ships. The following particular description will be set forth in connection with such slurry dewatering. However, it should be understood that the eductor jet pump of the present invention will find many other uses, including that of a variable metering device, or a solids or slurry pump and the like.

In the loading of pulpable slurries of mineral ores aboard ships or into other vessels, it is required that the suspending liquid be progressively eliminated before or in the course of transporting such material from the point of loading to destination. As the liquid is removed from the freshly loaded material, its volume may be restored by additional slurry and liquid, a compact economically transportable mass is obtained which is not free flowing so that vessel stability is obtained.

The present invention finds particular use in the ship loading of ore or mineral solids in slurrified form in which the iron ore is of a magnetic type which has been crushed, milled and beneficated to produce discrete particulate solids, the bulk of which may have a size ranging down from l mesh. The dry specific gravity of the ore may be of the order of 4.5 and the settling rate in water as a suspending liquid is relatively high. Typically, such ore solids are pulped with water to form pumpable slurries which contain at least 60% and up to 80% solids. The present eductor jet pump permits the elimination or removal of supernatant water from such settled slurries after they have been loaded into holds.

Heretofore, eductor jet pumps have been used for removing such supernatant liquids but they have not been entirely satisfactory due to the high pumping heads that are often required when pumping from deep within the holds and the change in head which results from the change in level of supernatant water during successive cycles of loading. That is to say, initially dewatering takes place from deeper portions within the hold of the ship, while at later stages of loading, the pump operates at more elevated positions. Present pumps do not account for the change in efficiency due to this change in the pumping head. Furthermore, when pumping against a high head from deep within a vessel, the pump is subject to back flooding of the entire head standing in the discharge line when the same is turned off. Such flooding can result in substantial inefficiencies since a considerable volume of water is released back into the freshly dewatered slurry. There is, therefore, a need for a new and improved eductor jet pump for use in the removal of supernatant liquids from settled slurries.

In general, it is an object of the present invention to provide an eductor jet pump and method which will overcome the limitations and disadvantages by the use of the foregoing a rapidly variable relationship between throat and a high velocity fluid jet.

Another object is to provide an eductor jet pump and method of the above character which facilitates the eliminating of settled supernatant liquid from previously suspended slurries.

Another object of the invention is to provide an eductor jet pump and method of the above character which will facilitate cyclic loading and dewatering of ore slurries to insure solidified non-shifting cargo dur' ing transit.

Another object of the invention is to provide an eductor jet of the above character in which the venturi throat cross section is variable during operation and which can be shut off completely to prevent back flow.

Another object of the invention is to provide an eductor jet pump and method of the above character in which the efficiency is variable and may be adjusted to suit the operation at various elevations.

Another object of the invention is to provide an eductor jet pump and method of the above character in which venturi throat cross section is varied regularly over a given cycle interval to provide pulsating operation.

The eductor jet pump and method of the present invention are particularly suitable for the dewatering of settled slurries in ship's holds and includes a discharge line terminating at its outer end in a jet nozzle which is directed into the throat. The nozzle is mounted for reciprocal movement towards and away from the throat to allow metering of the intake flow or to permit closure with the nozzle to shut the section flow off entirely. A hydraulic circuit is provided through the action of suitable cylinders to control the position of the jet with respect to the throat. Such position may be ad justed to a fixed position to control metering of flow through the throat or may be set for cyclic operation in which the jet is moved toward and away from the throat through a given number of strokes per minute to thereby provide pulsating operation. These and other objects and features of the invention will become apparent from the following description and claims when taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following description will be given in connection with the installation of an eductor jet pump and its use aboard ship, particularly for the dewatering of supernatant liquid from settled slurries. Typically, mineral slurries of this type settle rapidly and into a lower zone wherein the solids are in direct physical contact over laid with the zone in which the solids are still in the pro cess of settling and the third or upper zone which is es sentially quiescent and clarified liquid from which the solids are removed. Eventually a well defined plane of demarcation develops between the settling and settled zones and the upper zone of essentially clear liquid. The present invention contemplates removing of the suspending liquid by lowering the eductor jet pump of the present invention into the clarified supernatant liq aid and pumping the same off. after which additional slurry may be pumped in and progressively dewatered in the same manner.

Accordingly, referring to FlGS. I through 3 there is shown an eductor jet pump of the present invention which includes a discharge line mounted on the suitable support structure such as a bulkhead (not shown). The discharge line is of relatively large diameter and is connected by a swivel union (not shown) to a discharge conduit leading overboard The other end of the discharge line may be supported by a hoisting davit pro vided on the upper deck having a block and line connected to a pad eye at the outer end of the discharge line. The lower end of the discharge line terminates in means forming a venturi throat 12 which preferably is bell-shaped in a continuous annular curve.

A high velocity input line 14 is provided for supply fluid. such as a liquid, and includes ajet nozzle 16 at its lower end directed doaxially into the venturi throat in an operating position proximate thereto. Suitable means are provided for supporting the input line in sub stantially parallel relation to the discharge line and for moving the lower portion thereof so that the nozzle 16 can be brought towards and away from the venturi throat [2. Such means takes the form of a series of yokes 18. 20 regidly attached to the discharge line and carrying

bushed guides

22, 24 thereon for receiving the moveable portion 25 of the input line. An additional yoke 26 is attached to the input line at a position such that an extension thereof in the form ofa guide shoe 27 rides on the discharge pipe immediately above the ven turi nozzle to aid in preventing gross rotation of the members about each other. The lower end of the discharge line is U-shaped so that the nozzle 16 is directed in coaxiai relationship toward the venturi throat. As shown in FIGS. 1 and 3, a plurality of straightening vanes 29 are mounted to extend radially from the input line walls to aid in reducing vortex formation and re sulting turbulence and thereby increase the efficiency of the jet.

A resilient lining 28 is provided on the interior walls of the venturi throat. Preferably such lining is elastomeric and may be constructed of a suitable rubberlike formulation such as one of the urethane rubbers. The exterior of the nozzle is so sized that with respect to the throat, that when the nozzle is brought up into the throat. scaling contact is made with the elastomeric lining to thereby close the throat as a check valve to seal the same against backwash in the reverse direction down the discharge line.

Actuator means are provided at the upper end of the input line for varying and controlling the position of the nozzle either at some selected location or for recipro eating the same during the operation of the eductor. Such means takes the form of a bell 30 mounted at the upper end of the input line section 25 and forming a cylinder. The portion 25 of the input line between the bell and nozzle is thus moveable being supported for reciprocating motion in guides 22, 2.4. A fixed portion 4 32 of input line 14 is supported on discharge line 10 by a suitable double yoke support 34 and extends downwardly into the cylinder formed by the bell. The bell is provided with a pair of spaced seals 36, 38 which engage the side wall of the downwarly extending fixed portion of input line. The input line carries a fixed position piston 40 which together with the bell defines a volume of a double acting cylinder together with the seals 36. 38. The ends ofthe cylinder are provided with

hydraulic inlets

42, 44 so that the cylinder and the associated lower end of the discharge of the input line may be given up or down by application of hydraulic pres sure difference on an appropriate side of the piston 40.

Control means are provided for operating the actuator means and for establishing the position of the moveable portion 25 of the input line and the associated nozzle and consists of a parallel circuit including in one branch a four-way hydraulic valve 45 having

operational outputs

46, 48 connected to the

inlets

42, 44 on each side of the cylinder and a drain or relief line 49 passed through a mete ring valve 50 which partially controls the speed of movement of the apparatus. Screw adjustable limit stops 52, 54 are carried on the cylinder and actuate a level control 510 on an auto valve 51 forming the other branch of the circuit, and indicate the desired extremes of limited travel of the cylinder up or down, as indicated by the dotted outline 59 showing the uppermost or closed position. The stops serve to operate the auto valve and thereby reverse the pressure distribution and the direction of travel of the moveable input line at each extreme. Fluid pressure to the auto valve is supplied through a take-off line and a main shut-off valve 60 from the high pressure input line,

Means are provided for sensing the nature of the material flowing in the discharge line and for overriding the hydraulic control circuits to thereby close the venturi throat on the occurrence of certain predetermined conditions. Such means consist of

suitable sensors

61, 62 mounted on the discharge line. Sensor 61 is responsive to flow in the discharge line and operates upon cessation of the flow to energize the solenoid 64 on valve 45 to close the throat and prevent backwash. Sensor 62 senses solids content, as in the case of magnetic iron ore by measuring changes in the magnetic field. When the ore solids content becomes too great, sensor 62 energizes the second solenoid 64 on valve 45 to close the nozzle in the throat. When the discharge line is closed completely, high pressure water is the only element in' troduced into the discharge line and acts to force any obstruction of high solids load out.

Together, the actuator means and the control circuit serve to permit continuous control of the nozzle throat opening during the operation of the eductorv Thus. the present invention provides considerable flexibility in operation by permitting most efficient use at variable levels by moving the relative position of the nozzle to the throat to control the amount of throat opening. When pumping maximum depths the throat nozzle opening is narrowed to restrict the amount of material taken in and thereby develop a higher pumping head. in cyclic loading operations in which slurries are successively loaded and dewatered, the eductor is higher at the end of the loading cycle and the pumping head reduced. At that time the throat can be opened up to take up the maximum volume. When the nozzle is in completely closed position. it compresses against the rubber lining 28 of the throat and makes a completely tight seal. By using such a lining it is also possible to reduce the possibility of a rock holding the nozzle in partially opened position. Of course, at the end of each loading cycle, the throat is closed and the eductor moved up out of the way from the receiving vessel so that additional slurry can be pumped in. Thus, the adjustable feature of the present eductor allows use of maximum efficiency of the venturi throat opening which corresponds to various elevations and the volume of liquid decreases as the nozzle closes the throat area. And, the eductor lift does not stall as it would if the nozzle were used in a fixed single position. Additionaly, by shutting off the eductor, backflooding of the standing head in the discharge line back is completely prevented.

In addition to the using of the adjustable throat feature, the present invention can also be operated in a reciprocating mode in which the nozzle is moved toward and away from the throat over a predetermined distance and during a predetermined cycle time to vary the rate in amount of eduction for supply to the liquid charge being educted. In that mode of operation, the adjustable limit stops 52, 54 on the moveable portion 14 of the intake line serve to drive the operating lever 51a on the auto valve 51. By adjusting metering valve 50, the rate of movement of the intake line may be adjusted to determine the number of cycles per minute which are used. Generally, repeat time in the range of about 1 to 5 seconds for each complete cycle is found satisfactory. When so arranged, the jet automatically reciprocates and in each cycle gulps in a load of liquid which then moves up the throat and is pushed out of the discharge line. Meanwhile the eductor retracts to pick up another load and proceeds continually to discharge the liquid in a series of pulsations. Such operation is expected to be most useful in pumping slurries with the present eductor.

Referring now to FIG. 4, there is shown an alternative embodiment of the invention utilizing a pair of

double acting cylinders

80, 82 mounted on each side of the fixed portion 84 of the input high pressure line and having actuating

arms

86, 88 extending downwardly to connect to a suitable flange 90 carried on the moveable portion 92 of the input line which is sealed to the fixed portion for sliding movement by suitable single packing 94. This arrangement facilitates construction of the present invention utilizing conventionally available components.

An additional feature illustrated in FIG. 4 concerns the lateral position control of the nozzle. At the lower end of the bell 12 forming the venturi throat there is provided an outwardly extending annular rim 96 having guide holes therein. The end of the input line immediately beneath the nozzle is provided with an annular flange 98 carrying

guide rods

99, 100 mounted in alignment with the guide holes in the rim 96 and in alignment with the desired movement of the nozzles toward the venturi. In this way, forces subjected to the eductor during its operation will be unable to carry the nozzle too far out of misalignment and thereby either hinder its ability to seat into closure if desired or impair its efficiency by lateral mispositioning. The foregoing embodiments illustrate operation in which the throat-noz zle relationship is determined by movement of the nozzle and portions of the associated fluid supply. It is obvious that the discharge line could, alternatively, be constructed to move relative to a fixed nozzle by interchanging certain parts between the respective lines. Accordingly, any procedure for rapidly adjusting the relative positions of the throat and nozzle should be comprehended within the scope of the present invention.

While there has been disclosed herein certain specific embodiments in order to illustrate the carrying out of the present invention, it should be understood that they are to be taken in the illustrative sense, as many changes and adaptations of the present invention will occur to those skilled in the art to which it pertains. For example, while there has been shown the use of a hydraulic system for controlling the inlet line 14 position driven from the high pressure line supply itself, a separate hydraulic circuit could be used and even operate on a different media such as oil. In fact, it even is possible to use mechanical actuators with some loss in ease of operation. Many other applications of the invention besides dewatering of sl urries will suggest themselves to those skilled in the art. For example, the eductor jet pump of the present invention should find direct application as a proportioning device in which an additive is to be mixed with a slurry or liquid as in fire fighting ap plications. Also, the use of air, air-liquid mixtures, or other gas and gas-liquid mixtures could be used in the high pressure jet supply for where the additional buoyancy created was required to obtain satisfactory lift. Accordingly, the invention should be construed broadly, and should only be limited by the scope of the appended claims.

l claim:

1. A method for removing supernatant liquid or other material from a vessel or pool provided with apparatus including an eductor jet submerged in said liquid and having a nozzle in a discharge relationship with a Venturi throat section of a discharge conduit, comprising the steps of pumping a high velocity liquid through the nozzle as a jet directed into said throat to educt there with a charge of said liquid through said discharge conduit, moving said nozzle toward and away from said throat section over a given cycle time to vary the rate and amount of eduction force applied to each charge of liquid, and sensing the character of the discharge of the liquid in the discharge line, and closing the nozzle unit into sealing engagement with the throat section whenever the character of the discharge indicates that the solids content thereof exceeds the predetermined level or that flow rate falls below a predetermined value.

2. A method for removing supernatant liquid or other material from a vessel or pool provided with apparatus including an eductor jet submerged in said liquid and having a nozzle in a discharge relationship with a Venturi throat section of a discharge conduit, comprising the steps of pumping a high velocity liquid through the nozzle as a jet directed into said throat to educt therewith a charge of said liquid through said discharge conduit and cycling the nozzle toward and away from said throat section over a given cycle time in a regularly repeating cycle to vary the rate and amount of eduction force applied to each charge of liquid.

3. A method as in claim 2, wherein the period of the regularly repeating cycle has a value in the range from about I to 5 seconds for each complete cycle.

4. The method as in claim 3 in which said nozzle and throat section are constructed to form a seal therebetween when said nozzle is moved into engagement with said throat and further including the step of preventing backwash in the discharge conduit by bringing the nozzle and throat section into sealing engagement.

=i l 1: l

Claims

1. A method for removing supernatant liquid or other material from a vessel or pool provided with apparatus including an eductor jet submerged in said liquid and having a nozzle in a discharge relationship with a Venturi throat section of a discharge conduit, comprising the steps of pumping a high velocity liquid through the nozzle as a jet directed into said throat to educt therewith a charge of said liquid through said discharge conduit, moving said nozzle toward and away from said throat section over a given cycle time to vary the rate and amount of eduction force applied to each charge of liquid, and sensing the character of the discharge of the liquid in the discharge line, and closing the nozzle unit into sealing engagement with the throat section whenever the character of the discharge indicates that the solids content thereof exceeds the predetermined level or that flow rate falls below a predetermined value.

3. A method as in claim 2, wherein the period of the regularly repeating cycle has a value in the range from about 1 to 5 seconds for each complete cycle.