Abstract:
A liquid jet pump for moving a wide variety of material is described. The liquid jet pump is comprised of a nozzle assembly and a target tube, and defines a suction chamber. The nozzle assembly is configured to pull in gas, causing a gas bearing effect wherein a layer of gas surrounds the liquid jet flow exiting the nozzle assembly. The liquid jet passes through the suction chamber with minimal deflection, reducing cavitation and improving mixing as educted materials enter the suction chamber and combine with the liquid jet. The combined material is directed into the target tube, which preferably is designed to detach from the other components and is composed of abrasion-resistant material. The target tube absorbs the majority of wear, and provides ease of changing parts. The nozzle assembly is preferably positioned within the suction chamber in a way which maximizes vacuum, and the vacuum is maintained in relation to the pressure or vacuum produced by a downstream pump in a unique way, by controlling the gas flow into the nozzle assembly. In this way, the pump realizes drastic and surprising increases in solids pumping efficiency and solids/liquid mixing efficiency.

Description:
REFERENCE TO RELATED APPLICATION 
     This is a continuation-in-part of commonly owned and U.S. patent application Ser. No. 09/482,995, filed on Jan. 13, 2000, which issued as U.S. Pat. No. 6,322,327 on Nov. 27, 2001 the disclosure of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates generally to hydraulic nonmechanical pumping devices for transferring material, and specifically, to jet pumps for moving solid, semi-solid and/or liquid materials, as well as methods which employ such devices. 
     BACKGROUND 
     Numerous types of pumps have been developed for moving matter from one location to another. Typically, the physical and/or chemical nature of the material being moved by the pump plays an important role in pump efficacy. For example, the dredging industry commonly utilizes large centrifugal pumps for suction and movement of slurry material, i.e., water or other liquid in admixture with solid particulate matter, e.g., sand or gravel. Because of the abrasive characteristics of particles within such slurry material, these pumps typically suffer wear and tear and significant downtime to repair equipment components, especially moving parts which come into direct contact with the particulate matter. 
     Another dredging technique involves the use of air to induce an upward flow of water. This technique has typically involved compressed air or gas, requiring expensive compression equipment. In addition, the combination of gas, water and solids has contributed to process instability in the mixing chamber of the device, as discussed in U.S. Pat. No. 4,681,372. 
     Other hydraulic pumps employed in dredging and deep sea mining operations employ jet eduction systems, in which water is forced through piping configurations to cause an upward flow that pulls the water and solid material from the desired location. However, many jet eductor systems are flawed in that their high pressure water jets, while effective at removing high volumes of slurry material, cause severe cavitation in the throat and mixing regions of the eductor conduit, and result in lowered efficiency and extremely short equipment life, as discussed in, e.g., U.S. Pat. No. 4,165,571. 
     Other jet eduction systems have used atmospheric air for the purpose of creating air bubbles for separation processes, as in U.S. Pat. No. 5,811,013. These systems are not designed to increase pump efficiency, prevent pump cavitation or increase pump flow as disclosed by the present invention. However, U.S. Pat. No. 5,993,167 does disclose a jet eduction system which permits air to form a layer surrounding a high pressure flow of liquid, which is directed through a space and into a tube, thereby forming a vacuum in the space. Yet, this system does not produce vacuum sufficient for many commercial operations, and does not provide for control of the weight percentage of solids in pumped slurries. 
     Thus a need continues to exist for a commercially viable jet eduction system which moves large volumes of matter with very little wear and tear on the system. A need also exists for systems which enabling users to achieve greater pumping efficiency. 
     SUMMARY OF THE INVENTION 
     The present invention overcomes the shortcoming of prior developments by providing, among other things, a pumping system which can (a) increase the quantity of material moved, relative to previously developed pumps, without an increase in energy consumption, (b) move solid materials with minimal wear on component parts, (c) overcome the problems associated with traditional venturi effect pumps, (d) include specific component parts which are designed to wear and which can be easily changed, (e) produce a vacuum for suctioning material with little or no cavitation, and/or (f) enable the control of the solid to liquid ratio of the material being pumped to drastically increase the pumping efficiency. Moreover, the present invention provides an efficient mixing system which employs a jet pump of this invention and enables users to rapidly form a liquid and solid material mixture, preferably one in which the mixture is substantially homogeneous, to control the weight percent of solids in the resulting mixture, and to efficiently transport the mixture downstream from the jet pump to a desired location. 
     Thus, in one embodiment of the present invention, an improved liquid jet pump is provided. The liquid jet pump is comprised of a nozzle assembly that pulls in atmospheric air. The liquid jet created by passage of liquid through the nozzle assembly has minimal deflection as it exits because of an atmospheric air bearing surrounding the liquid jet. Consequently, the liquid jet pump has improved efficiency and capacity. The liquid jet pump is configured to define a suction chamber and further comprises a suction pipe. The suction pipe pulls in the material to be pumped as the liquid jet from the nozzle assembly passes through the suction chamber. The liquid jet pump further comprises a target tube that receives the liquid jet combined with material to be pumped which enters the suction chamber after traveling through the suction pipe. The target tube is comprised of a housing support detachable from the suction chamber and a wear plate of abrasion-resistant material. 
     In another embodiment, this invention provides apparatus which is comprised of(a) a nozzle assembly which is sized and configured to (i) receive a pressurized liquid and a gas, and (ii) eject the pressurized liquid as a liquid flow while feeding the gas into proximity with the periphery of the liquid flow; (b) a housing defining a suction chamber into which the nozzle assembly may eject the liquid flow, the housing also defining a suction inlet and a suction outlet; (c) an outlet pipe extending from the suction outlet away from the suction chamber housing, said outlet pipe being configured for liquid communication with the suction chamber and being disposed to receive the liquid flow; the outlet pipe defining at least a first inner diameter along a portion of its length and a second inner diameter along another portion of its length, the second inner diameter being less than the first inner diameter; and (d) a suction pipe, a first end of the suction pipe opening into the suction chamber at the suction inlet, and a second end of the suction pipe opening into the surrounding environment; wherein the nozzle assembly extends into the suction chamber towards the suction outlet and into the imaginary line of flow of the suction pipe. 
     In another embodiment, this invention provides a pumping system comprising: (a) a nozzle assembly which is sized and configured to (i) receive a pressurized liquid and a gas, and (ii) eject the pressurized liquid as a liquid flow while feeding the gas into proximity with the periphery of the liquid flow; (b) a housing defining a suction chamber into which the nozzle assembly may eject the liquid flow, the housing further defining a suction inlet and a suction outlet; (c) an inlet pipe for providing pressurized liquid to the nozzle assembly; (d) a gas conduit for providing the gas to the nozzle assembly; (e) an outlet pipe extending from the suction outlet away from the suction chamber, the outlet pipe being configured for liquid communication with the suction chamber and being disposed to receive the liquid flow; the outlet pipe defining at least a first inner diameter along a portion of its length and a second inner diameter along another portion of its length, the second inner diameter being less than the first inner diameter; and (f) a suction pipe, a first end of the suction pipe opening into the suction chamber at the suction inlet, and a second end of the suction pipe opening into the surrounding environment. This invention also provides a system for dredging matter from the bottom of a body of water, the system comprising: (a) a pumping system as described above in this paragraph, (b) a buoyant platform equipped to raise and lower at least a portion of the pumping system relative to the bottom of the body of water, and (c) a first pump for providing the pressurized liquid to the nozzle assembly. 
     In yet another embodiment of the present invention, a method of moving, from one location to another, a slurry comprised of a solid and a liquid, is provided. The method comprises: 
     a. injecting a pressurized liquid into a nozzle assembly to produce a flow of pressurized liquid, 
     b. providing a gas to the nozzle assembly to surround the flow of pressurized liquid with the gas, 
     c. directing the flow of pressurized liquid surrounded by the gas into a suction chamber in fluid communication with a suction pipe and an outlet pipe, the outlet pipe defining a venturi-like inner surface, and directing the flow of pressurized liquid surrounded by the gas toward the outlet pipe to produce a vacuum at a free end of the suction pipe, and 
     d. controlling the flow rate of the gas into said nozzle assembly to thereby control the weight ratio of solid to liquid in the slurry so moved. 
     These and other embodiments, objects, advantages, and features of this invention will be apparent from the following description, accompanying drawings and appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of one preferred dredging assembly embodiment of this invention. 
     FIG. 2 is a sectional view of the jet pump component of the assembly of FIG.  1 . 
     FIG. 3 is a sectional view of the jet pump components indicated on FIG.  2 . 
     FIG. 4A is a sectional view of a preferred embodiment of the nozzle assembly showing minimal deflection of the liquid jet. 
     FIG. 4B is a sectional view of an embodiment of the nozzle assembly showing deflection of the liquid jet. 
     FIG. 5 is a perspective view of material moving through the nozzle assembly and suction chamber. 
     FIG. 6 is a perspective view of a preferred embodiment of the nozzle assembly, suction chamber and target tube of the invention. 
     FIG.  7  and FIG. 8 are sectional views of a preferred embodiment of the nozzle assembly of the invention. 
     FIG. 9 is a sectional view of another jet pump component of this invention which is an alternative to that illustrated in FIG.  2 . 
     FIGS. 10 and 11 are sectional views the nozzle assembly from the jet pump component of FIG.  9 . 
    
    
     In each of the above figures, like numerals or letters are used to refer to like or functionally like parts among the several figures. 
     DETAILED DESCRIPTION OF THE INVENTION 
     It will now be appreciated that, while specific embodiments are described hereinafter, several other applications of the presently described invention may be contemplated by those of skill in the art in view of this disclosure. For example, while the accompanying drawings illustrate the pumping system of this invention as used for dredging operations, the system may be used for virtually any application in which solid particulate matter, e.g., or a slurry comprised of such matter, must be moved from one location to another. The system also may be employed to remove liquids from such slurry mixtures, thereby permitting solid particulate matter to be rapidly separated from the liquid and dried, if desired. In each of the above examples, small batch operations as well as large commercial batch, semi-continuous and continuous operations are possible using pumping methods and systems of this invention. 
     The gas employed in the pumping systems and methods of this invention will preferably be under no more than atmospheric pressure, to reduce risk of operations and cost. The gas preferably will be an inert gas, e.g., nitrogen or argon, when the liquid or other material being pumped could be volatile in the presence of certain atmospheric gases, e.g., oxygen. When such volatility is not an issue, the gas employed will be most conveniently atmospheric air. 
     Turning now to the drawings, FIG. 1 illustrates one preferred embodiment of this invention, in use on a barge  100  for dredging solid materials from a water source, such as a lake or river. Barge  100  is equipped with a cantilever system  101  to raise and lower a suction pipe  102  into the water source. Suction pipe  102  is connected to a jet pump  107  configured in accordance with this invention and further described hereinafter. 
     A discharge (or “inlet”) pipe  103  feeds water or other liquid pumped by a pump  104  to jet pump  107 . Pump  104  is typically a centrifugal pump, but can be any kind of pumping means, such as a positive displacement pump or even another jet pump. Pump  104  can be contained in a pump housing  105 . Discharge pipe  103  also feeds water or other liquid to a supplemental jet nozzle assembly, illustrated here as a jet nozzle  106 , upstream from jet pump  107  and suction pipe  102 . Jet nozzle  106  is sized and configured to project a pressurized liquid flow into the surrounding environment, to thereby break up solid material to facilitate its incorporation into the material pumped by jet pump  107 . 
     The depiction of the preferred embodiment of this invention for use in the dredging industry reflected in FIG. 1 is only one illustrative example of the numerous applications in which embodiments of this invention may be employed. Jet pump  107 , for instance, can vary in size, from handheld unit to mounted on a bulldozer, mudbuggy or other vehicle, for use in various applications. The distance between pump  104  and jet pump  107 , i.e., the length of the discharge pipe, can also vary greatly. 
     FIGS. 2 and 3 illustrate jet pump  107  in greater detail. Jet pump  107  includes nozzle assembly  307  (FIG. 3 only), which in turn is comprised of a fluid nozzle  201 , an air injection nozzle  202  and a nozzle housing  203 . Nozzle housing  203  is a flanged member which is attached to and maintains the proper position of fluid nozzle  201  adjacent to air injection nozzle  202 . Air intake  211  is one or more passages through nozzle housing  203 . In the embodiment depicted, a single air intake  211  is shown although those skilled in the art could use more. A gas conduit in the form of an air hose  204  provides a gas to jet pump  107  and allows jet pump  107  to use air even when below the water level. nozzle  202  and a nozzle housing  203 . Nozzle housing  203  is a flanged member which is attached to and maintains the proper position of fluid nozzle  201  adjacent to air injection nozzle  202 . Air intake  211  is one or more passages through nozzle housing  203 . In the embodiment depicted, a single air intake  211  is shown although those skilled in the art could use more. A gas conduit in the form of an airhose  204  provides a gas to jet pump  107  and allows jet pump  107  to use air even when below the water level. 
     Water or other fluid supplied by a pumping means passes through discharge (or “inlet”) pipe  103 , fluid nozzle  201 , and air injection nozzle  202  into a housing  200  which defines a suction chamber  205 . In suction chamber  205 , the fluid in the form of a liquid flow combines with material entering chamber  205  from suction pipe  102  via a suction inlet  109 , and the combined stream enters a target tube  206  disposed within an outlet pipe  207  through a suction outlet  110  of chamber  205 . The combined stream then passes through target tube  206  into outlet pipe  207   
     In a preferred embodiment jet nozzle  106  extends from discharge (or “inlet”) pipe  103 , allowing a portion of the forced fluid supplied by pumping means to pass through jet nozzle  106 . In a similar manner to the configuration for jet pump  107 , jet nozzle  106  contains a venturi  208  at its end opposite the end connected to discharge pipe  103 . Venturi  208  is equipped with air hose  210  to allow entry of atmospheric air at aperture  209  when jet pump  107  is submerged. 
     Jet nozzle  106  extends approximately the same length as suction pipe  102  and, as depicted in FIG. 1, terminates approximately one (1) foot from the open end of suction pipe  102 . Fluid forced through jet nozzle  106  exits venturi  208  with air into the material that will be suctioned. An air bearing effect minimizes deflection and allows deeper penetration to loosen to the material being transferred. The jet stream also creates a churning effect that directs the churned material into the open end of suction pipe  102 . 
     Although jet nozzle  106  is shown in FIGS. 1 and 2 as a single attachment, in an alternate embodiment, multiples of jet nozzle  106  can be attached to discharge pipe  103 . In another embodiment, one or more jet nozzles  106  can be attached to suction pipe  102 , handheld, or mounted on other equipment, depending on the application. 
     Referring to FIGS. 3,  4 A and  4 B, in the interior of nozzle housing  203 , fluid nozzle  201  includes constricted throat  301 . Fluid nozzle  201  is attached by a connecting means to air injection nozzle  202 . Air gap  302  exists between constricted throat  301  and air injection nozzle  202 . In one embodiment, air gap  302  between constricted throat  301  and air injection nozzle  202  at its narrowest point measures {fraction (3/16)} of an inch. The overall area and dimension at the narrowest point of air gap  302  will vary with the application and the material being transferred to optimize the suction effect. 
     Fluid nozzle  201  is attached to air injection nozzle  202  by means of nozzle housing  203 . Nozzle housing  203  is a flanged pipe with air intake  211  drilled into the pipe circumference. Although nozzle housing  203  is depicted with one air intake  211 , those skilled in the art would know that multiple air intakes can be provided. 
     Air injection nozzle  202  is provided with one or more air holes  304 . In a preferred embodiment depicted in FIG. 6, air injection nozzle  202  has eight ½ inch holes  304  equal distance around the circumference of air injection nozzle  202 . 
     When air injection nozzle  202  and fluid nozzle  201  are assembled, one of air holes  304  can align with air intake  211 . Alignment however is not necessary, as air injection nozzle  202  further defines an annular trough  602  in its outer surface into which air holes  304  open, thereby providing a path for air flow around the circumference of nozzle  202  and into each of holes  304 . 
     Air hole  304  and air intake  211  allow the entry of atmospheric air to fill air gap  302 . The forced delivery of liquid through constricted throat  301  creates a vacuum in air gap  302  that pulls in atmospheric air. Varying the amount of air entering air hole  304  creates an increased suction effect in air gap  302 . 
     In one embodiment, vacuum in air gap  302  measured 29 inches Hg when air intake  211  was 10% open, compared to 10 inches Hg when air intake  211  was 100% open. Restriction of air though air intake  211  can be accomplished by any mechanical valve means, e.g., such as that depicted as valve  212 . 
     Without being bound to theory, it is believed that entry of a gas (e.g., air) into air gap  302  creates a gas bearing effect. The air surrounds the flow of fluid leaving constricted throat  301  and the combined fluid jet with surrounding air passes through air injection nozzle  202 . 
     Referring to FIGS. 2,  3 , and  5 , the fluid jet with the air, introduced through air gap  302 , exits air injection nozzle  202 , passes through suction chamber  205 , and enters target tube  206 . The combined air fluid jet passes through suction chamber  205  with minimal deflection before entering target tube  206 . 
     As illustrated approximately in FIGS. 3,  4 A and  4 B, a visual correlation can be observed between the deflection of a liquid jet entering target tube  206 , and the presence of atmospheric air in air gap  302 . FIG. 4A shows the liquid pattern with atmospheric air creating air bearing  501 . FIG. 4B depicts the liquid pattern exiting air injection nozzle  202  without atmospheric air present. For the embodiment depicted, the best results for pumping only water were achieved when the pump discharge pressure was 150-175 p.s.i. and the vacuum in air gap  302  was 18-22 inches of Hg. 
     Air bearing  501  around the liquid jet minimizes deflection, and thus, cavitation in suction chamber  205 . Less cavitation reduces wear and the need to replace component parts, and increases flow through suction chamber  205  into target tube  206  with the liquid jet stream. 
     Referring to FIG. 3, suction chamber  205  is shown with suction pipe  102  entering at a 45° angle. The design of suction chamber  205  allows one to adjust the placement of air injection nozzle  202  so that air injection nozzle  202  is out of the flow of solid material entering suction chamber  205 , so as to prevent wear, or further into suction chamber  205  so as to create a greater vacuum. 
     Suction pipe  102  entering at an angle avoids the problem common to many eductor nozzles suffering excessive wear and corrosion by being placed in the flow of solid material. Although this configuration is a preferred embodiment to maximize the entry of slurry material with minimal abrasive effect, those skilled in the art would know that alternate angles greater than 0° and less than 180° can be utilized. 
     In the embodiment depicted, suction chamber  205  measures 24¾ inches at A. The distance between nozzle opening  303  and one end of target tube  206  is 13¾ inches at B. 
     As the liquid jet passes through target tube  206 , a suction effect is created in suction chamber  205 . The suction effect pulls in any material located at open end of suction pipe  102 . The suction effect increases the overall quantity of material driven by pump  104 . The following Table 1 illustrates the ratio of total material exiting target tube  206  to pumped liquid entering fluid nozzle  201 : 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                   
                   
                 Liquid 
                   
                   
                   
               
               
                   
                   
                 Exit 
                 Liquid Inlet 
               
               
                 Pump 
                 Vacuum 
                 Power 
                 Fluid 
                 Suction 
               
               
                 Discharge 
                 Measured In 
                 (gallons 
                 Nozzle 
                 Ratio 
                 Discharge 
               
               
                 Pressure 
                 Air Gap 
                 per 
                 (gallons per 
                 Tube 
                 Pressure Exit 
               
               
                 (psia) 
                 (inches Hg) 
                 minute) 
                 minute) 
                 (psia) 
                 (psia) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 100 
                 25 
                 3160 
                 672 
                 4.70 
                 6 
               
               
                 125 
                 25 
                 3500 
                 780 
                 4.49 
                 7 
               
               
                 150 
                 25 
                 4150 
                 824 
                 5.04 
                 8 
               
               
                 175 
                 25 
                 4460 
                 890 
                 5.01 
                 9 
               
               
                 200 
                 25 
                 4080 
                 950 
                 4.29 
                 9.5 
               
               
                 225 
                 25 
                 4500 
                 1000  
                 4.50 
                 9.5 
               
               
                 250 
                 25 
                 4500 
                 1063  
                 4.23 
                 10 
               
               
                 100 
                 20 
                 3140 
                 672 
                 4.67 
                 6 
               
               
                 125 
                 20 
                 3700 
                 780 
                 4.74 
                 6 
               
               
                 150 
                 20 
                 4050 
                 824 
                 4.92 
                 7 
               
               
                 175 
                 20 
                 4170 
                 890 
                 4.69 
                 8 
               
               
                 200 
                 20 
                 4150 
                 950 
                 4.37 
                 9 
               
               
                 225 
                 20 
                 3600 
                 1000  
                 3.60 
                 10 
               
               
                 250 
                 20 
                 3300 
                 1063  
                 3.10 
                 10 
               
               
                 100 
                 15 
                 3450 
                 672 
                 5.13 
                 6 
               
               
                 125 
                 15 
                 3911 
                 780 
                 5.01 
                 6 
               
               
                 150 
                 15 
                 4041 
                 824 
                 4.90 
                 7 
               
               
                 175 
                 15 
                 3600 
                 890 
                 4.04 
                 8 
               
               
                 200 
                 15 
                 3200 
                 950 
                 3.37 
                 9 
               
               
                 225 
                 15 
                 2300 
                 1000  
                 2.30 
                 10 
               
               
                 250 
                 15 
                 2700 
                 1063  
                 2.54 
                 10 
               
               
                   
               
             
          
         
       
     
     The specific gravity of the material pumped, i.e. water, versus sand or gravel, will affect the optimum inches vacuum in air gap  302  and the discharge pressure of pump  104 . During testing of jet pump  107 , vacuum in air gap  302  measured 29 inches Hg when suctioning water, 24 inches Hg when suctioning slurry material containing sand, and 18 inches Hg when suctioning material containing gravel. 
     The suction effect created by target tube  206  allows the movement of larger quantities of material without any concurrent increase in horsepower to operate pump  104  providing the liquid flow. For example, testing has demonstrated movement of material containing 60-65% by weight of sand, as compared to the 18-20% of solids using conventional methods such as centrifugal pumps at the same flow rate or discharge pressure. 
     Target tube  206  constitutes a segment of the outlet pipe in the form of a detachable wear plate in the preferred embodiment illustrated. The outlet pipe segment defines an inner surface, at least a portion of which in turn defines the second inner diameter of the outlet pipe. The target tube can be detached from outlet pipe  207  and suction chamber  205 . The majority of wear from abrasive material occurs in target tube  206 , not suction chamber  205 , because of reduced cavitation from the air bearing effect on the liquid jet and the design of suction chamber  205 . 
     In FIGS. 3 and 6, target tube  206  is fixably attached to target tube housing  306 . Once target tube  206  is worn, target tube  206  can be removed by detaching target tube housing  306  from suction chamber  205  on one end and outlet pipe  207  on the other end without having to open suction chamber  205 . 
     In an alternative embodiment, target tube  206  may be fixably attached at one end to a connecting means such as a split locking flange. The split locking flange could then hold target tube  206  in place at one end by connecting between outlet pipe  207  or suction chamber  205  and target tube housing  306 . The opposite end of target tube  206  could then rest on target tube housing  306  using notches or other means to prevent axial or radial movement. 
     A centrifugal dredge pump  108 , as shown in FIG. 1, can be placed downstream of target tube  206  despite the introduction of atmospheric air before nozzle opening  303 . No cavitation occurs in centrifugal dredge pump  108  from the atmospheric air. This is counter to conventional wisdom regarding operation of centrifugal pumps by those skilled in the art. The atmospheric air likely dissolves in the liquid jet in or past target tube  206 , further supporting the optimum effect observed when atmospheric air is restricted in its entry through air intake  211 . 
     Target tube  206  can vary in both length and diameter. Diameter will most often be determined by the particle size of the material conveyed. Length and diameter of target tube  206  will effect the distance and head pressure that jet pump  107  can generate. 
     In a preferred embodiment shown in FIG. 6, target tube  206  measures 36 inches in length, with 6⅝ inches outer diameter and 6 inches inner diameter. Target tube housing  306  is composed of two 6×12 inch reducing flanges, each connected to one end of 12¾ inch pipe 10 inches long. Interior target tube wear plate  305  (as shown in FIG. 3) is composed of abrasion-resistant material such as, e.g., metals with high chrome content. 
     As shown in FIG. 6, target tube  206  is a straight pipe with blunt edges. In an alternate embodiment shown in FIG. 2, target tube  206  could have angled edges of a larger diameter than the diameter of the target tube body at one or both ends of target tube  206 . 
     In a preferred embodiment, the nozzle elements of FIG. 7 are constructed according to specific proportions. Although the nozzle elements are shown as three separate elements, those skilled in the art would know that the nozzle assembly could be constructed of one or more elements of varying dimensions. Fluid nozzle  201  is 5 inches in length and 8 inches in outer diameter. Constricted throat  301  of fluid nozzle  201  at inner edge  701  narrows radially inward from 8 inches to 2 inches diameter at its narrowest point at a 45° angle. Fluid nozzle  201  measures 3 inches in diameter on outer edge  702 . 
     Air injection nozzle  202  is 12⅞ inches in length. At one end, air injection nozzle  202  is 10 inches in diameter on outside surface  703 , and 8.01 inches in diameter on inside surface  704 . Outside surface  703  remains 10 inches in diameter axially for a length of 5 inches, then drops radially to a diameter of 7 inches, and angles inward radially to a diameter of 4 inches for the remaining length. In a preferred embodiment, air injection nozzle  202  has an angle of 102° between the smallest diameter at angled end in the vertical plane and angled edge. 
     Inside surface  704  of air injection nozzle  202  remains 8.01 inches axially for a length of 4{fraction (3/16)} inches, then drops radially to a diameter of 2½ inches for the remainder of the length. 
     Air hole  304  is ½ inch in diameter equally spaced along the circumference of outside surface  703  located 2 inches from the end of air injection nozzle  202  that has a 10 inch diameter 
     In a preferred embodiment, nozzle housing  203  measures 13½ inches at flanged end  705  connected to fluid nozzle  201 . At flanged end  706  connected to suction chamber  205 , the outer diameter measures 19 inches. Flanged end  705  has an inner diameter measuring 7.0625 inches, sufficient to allow passage of air injection nozzle  202  at its angled end. Flanged end  705  has an inner diameter for the remaining length of 10.01 inches to accommodate air injection nozzle  202  at its largest point. Nozzle housing  203  has a 1 inch NPT connection in air intake  211 . 
     FIGS. 9,  10  and  11  illustrate another preferred embodiment of the present invention. This embodiment differs from the others illustrated in the previous figures in the configuration of the nozzle assembly and outlet pipe segment. As may be seen with reference to FIGS. 10 and 11, the nozzle assembly of this particular embodiment is comprised of a fluid nozzle  401 , an air pattern ring  402  A, an air injection nozzle  402 , and a nozzle housing  403 . In this configuration, ring  402  A can be replaced with modified rings when different air patterns are desired. Nozzle  402  is extended in length to permit the nozzle opening to be more proximate to target tube  406  (FIG. 9) without being so close to tube  406  so as to block larger particle size solids from passing from chamber  205  into tube  406 . Surprisingly, it has been found that nozzle  402  may extend into the imaginary line of flow of suction pipe  102 , represented on FIG. 9 with broken line Z, without suffering undue wear and tear as a result of solid material flowing into chamber  205 . Thus, increased vacuum may be achieved through nozzle extension without substantial adverse wear upon nozzle  402 . 
     It will also be appreciated from FIG. 9 that the outlet pipe is comprised of a target tube (labeled  406  in FIG. 9) which defines a first inner diameter Q, the outlet pipe also defining a second inner diameter R which is less than inner diameter Q. However, outlet pipes of this invention may also be fabricated without a target tube but with a non-uniform inner surface so as to define a narrowing passage, so as to provide a venturi-like effect to the material exiting the suction chamber. 
     To further illustrate the present invention, a pump incorporating the features of that illustrated in FIGS. 9-11 and having the following dimensions was employed to pump gravel, dirt and water from a gravel pit, and samples were taken to measure the percentage of solids which were pumped at various pressure settings. 
     jet nozzle: 
     inner diameter (“ID”)—2.5 inches, outer diameter (“OD”)—5⅞ inches, length (“L”, —7{fraction (1/16)} inches. 
     air nozzle: 
     ID—2¾ inches, OD—4 inches, L—17 inches. 
     air pattern ring: 
     1.5 inches width, ID—4 inches, OD—5⅞ inches, having eight 0.5 inch diameter annularly displaced apertures about its circumference. 
     outlet pipe segment: 
     ID—7 inches, L—35.5 inches and suction inlet ID—12 inches. 
     The setting during sampling and the results achieved are set forth in Table 2. 
     
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 2 
               
               
                   
               
               
                   
                   
                 Dredge Pump 
                   
                   
                   
                   
                   
               
               
                   
                 Jet Pump 
                 Vacuum 
                 Dredge 
                   
                 Line 
                   
                 Jet Pressure 
               
               
                   
                 Vacuum at 
                 downstream 
                 Pump 
                 Percent 
                 Velocity 
                   
                 upstream of 
               
               
                   
                 nozzle air 
                 from 
                 Discharge 
                 of 
                 from 
                   
                 nozzle 
               
               
                   
                 intake 
                 Jet Pump 
                 Pressure 
                 Solids 
                 Dredge Pump 
                 Tons per 
                 assembly 
               
               
                 Sample 
                 (inches Hg) 
                 (inches Hg) 
                 (psia) 
                 (wt %) 
                 (feet per second) 
                 Hour 
                 (psia) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 1 
                 20 
                 13 
                 70 
                 45 
                 14 
                 535 
                 105 
               
               
                 2 
                 21 
                 6 
                 74 
                 51 
                 14 
                 605 
                 105 
               
               
                 3 
                 25 
                 19 
                 75 
                 52 
                 14 
                 615 
                 105 
               
               
                 4 
                 26 
                 1 
                 84 
                 55 
                 14 
                 670 
                 105 
               
               
                 5 
                 27 
                 18 
                 77 
                 51 
                 14 
                 614 
                 105 
               
               
                 6 
                 23 
                 4 
                 80 
                 42 
                 14 
                 535 
                 115 
               
               
                 7 
                 24 
                 20 
                 75 
                 40 
                 13 
                 397 
                 115 
               
               
                 8 
                 25 
                 6 
                 80 
                 48 
                 13 
                 594 
                 115 
               
               
                 9 
                 26 
                 15 
                 80 
                 51 
                 13 
                 610 
                 115 
               
               
                 10 
                 27 
                 21 
                 75 
                 46 
                 14 
                 550 
                 115 
               
               
                 11 
                 24 
                 15 
                 75 
                 46 
                 13 
                 424 
                 125 
               
               
                 12 
                 26 
                 15 
                 80 
                 52 
                 14 
                 667 
                 120 
               
               
                   
               
             
          
         
       
     
     It is believed that, heretofore, production of 18-20 wt % solids was the best that could be expected from conventional deck mounted dredging pumps. However, as can be seen from the data presented in Table 2, percentages at or above 40 wt % solids, and more preferably at or above 50 wt % solids, pumped material are routinely achieved. Such results are most readily achieved in particularly in the embodiments of this invention by controlling gas flow so as to maintain gas entering the preferred assembly under a vacuum in the range of about 18 inches Hg to about 26 inches Hg, and operating the dredge pump at an intake pressure/vacuum in the range of about 5 inches Hg to about 5 psia. Pumping systems of this invention operated under these conditions enable particularly drastic and surprising improvements in pumping efficiency. 
     While it is understood that at least one preferred jet pump described herein is characterized by the entry of atmospheric air and a detachable outlet pipe segment forming a wear plate, it is apparent that the foregoing description of specific embodiments can be readily adapted for various applications without departing from the general concept or spirit of this invention. Thus, for example, the inner surface of the outlet pipe (which provides the venturi effect feature of the outlet pipe) alternatively can be defined by the pipe itself, rather than a detachable wear plate, and/or the gas entering the nozzle assembly can be an inert gas, e.g., nitrogen. In addition, an efficient mixing system and method are provided by this invention, whereby the jet pump described herein is employed to mix a liquid with solid or slurry material to form a mixture, wherein the weight percent of solids in the mixture is controlled by controlling the air intake vacuum and the dredge pump intake pressure/vacuum as described above. Such mixing systems facilitate mixing volatile materials by simply using an inert gas for the gas intake at the nozzle assembly. Mixtures made in accordance with this system are particularly uniform and can be substantially homogenous, presumably on account of the forces applied to the liquid and solid material in, for example, the suction chamber of jet pumps of this invention. 
     These and other adoptions and modifications are intended to be comprehended within the range of equivalents of the presently disclosed embodiments. Terminology used herein is for the purpose of description and not limitation. 
     The present invention can be used in any application requiring significant suction effect of solid material in a liquid or gaseous environment. Those skilled in the art would know that the invention can also be used for suction in gaseous or liquid environments without solids present, and maintain a significant suction effect. Thus, as noted earlier, the invention can also be used in closed loop de-watering applications to remove excess water or moisture from material. 
     The dimensions of the various component parts of devices of this invention may vary depending upon the circumstances in which the device will be employed, so long as the dimensions permit the components to function as described herein. Except where specifically noted otherwise herein, the component parts may be fabricated from a wide variety of materials, the selection of which will depend again upon the circumstances in which the device will be employed. Preferably, metals, metal alloys or resilient plastics, for example, will be employed to insure that points of mechanical contact or abrasive wear in the systems and pumps will be resilient enough to withstand the forces placed upon them during pump operation. 
     Each and every patent or printed publication referred to above is incorporated herein by reference in toto to the fullest extent permitted as a matter of law. 
     This invention is susceptible to considerable variation in its practice. Therefore, the foregoing description is not intended to limit, and should not be construed as limiting, the invention to the particular exemplifications presented hereinabove. Rather, what is intended to be covered is as set forth in the ensuing claims and the equivalents thereof permitted as a matter of law. As used in this specification, means-plus-function clauses are intended to cover the structures described herein as performing the cited function and not only structural equivalents but also equivalent structures.