Abstract:
An improved liquid jet pump for moving solid or other materials is provided. The liquid jet pump includes a nozzle assembly, a suction chamber, and a target tube. The nozzle assembly pulls in atmospheric air, causing an air bearing effect around the liquid jet exiting the nozzle assembly. The liquid jet passes through the suction chamber with minimal deflection, reducing cavitation and improving mixing as educted materials enters the suction chamber and combines with the liquid jet. The combined material is directed into the target tube, which 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.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of The Invention 
     This invention relates, generally, to hydraulic nonmechanical pumping devices for transferring material, and specifically, to an air-assisted liquid jet pump for moving solid materials. 
     2. Description of Related Art 
     The dredging industry commonly utilizes large centrifugal pumps for suction and movement of slurry material, i.e., water containing varying particle sizes such as sand or gravel. Because of the abrasive effect caused by particles, these pumps suffer wear and tear and significant downtime to repair parts of the equipment. 
     Removal of solid materials from a water environment by means of hydraulic operations is well known in the art. Dredging and deep sea mining operations employ water forced through piping configurations to cause an upward flow that pulls the water and solid material from the desired location. 
     A common problem in using jet eductor systems occurs because 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 U.S. Pat. No. 4,165,571. 
     Use of air to induce upward flow of water has also been used. Use 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. 
     Jet eduction systems have used atmospheric air for the purpose of creating air bubbles for separation processes in U.S. Pat. No. 5,811,013. These systems were not designed to increase pump efficiency, prevent pump cavitation or increase pump flow as disclosed by the present invention. Prior art teaches against introduction of air for these purposes. 
     Cavitation is the term used to describe vapor bubble generation and collapse in pumps when the pressure in the pump suction drops to or below the NPSH for the pump. The same effects can be observed when air enters the liquid stream inlet of a pump. The presence of a gas in both circumstances causes reduced capacity, reduced or unstable head pressure, and unstable power consumption. Vibration, noise, accelerated corrosion, fatigue failure and other mechanical damage are the consequences of cavitation. The use of the term cavitation in this specification is intended to cover the resulting effects rather than define the physical circumstances causing these resulting effects. 
     OBJECTS OF THE INVENTION 
     It is an object of the present invention to provide a pumping means that increases the quantity of material moved without an increase in energy consumption. 
     It is another object of the present invention to provide a pumping means for moving solid materials with minimal wear on component parts. 
     It is another object of the present invention to overcome the problems associated with traditional venturi effect pumps. 
     It is another object of the present invention to provide a pump that has specific parts which are designed to wear and which can be easily changed. 
     It is another object of the invention to provide a pump that produces a vacuum for suctioning material with little or no cavitation. 
     SUMMARY OF THE INVENTION 
     An improved liquid jet pump for moving solid materials is provided. The liquid jet pump includes a nozzle assembly that pulls in atmospheric air. The liquid jet created by passage 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 also includes a suction chamber with a suction pipe. The suction generated in the chamber pulls in solid material through the suction pipe as the liquid jet from the nozzle assembly passes through the suction chamber. The liquid jet pump also includes a target tube that receives the liquid jet combined with materials from the suction pipe through the suction chamber. The target tube includes a housing support detachable from the suction chamber and is composed of a wear plate of abrasion-resistant material. 
     An advantage of the invention is that pump efficiency is improved by increasing the quantity of solid material moved without an increase in horsepower. 
     A further advantage of the invention is that the target tube wear plate is removable without requiring disassembly and repair of the entire pipe configuration. 
     A further advantage of the invention is that cavitation in the suction chamber is significantly reduced thereby reducing wear and increasing suction. 
     A feature of the invention is that conventional centrifugal pumps can be used downstream of the liquid jet pump to increase overall lift capacity. 
     A further feature of the invention is that it employs no moving parts that can provide potential ignition sources, permitting it to be safely used to pump flammable or volatile material. 
     These and other objects, advantages, and features of this invention will be apparent from the following description. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a plan view of a dredging assembly with an embodiment of the invention attached. 
     FIG. 2 is a sectional view of a preferred embodiment of the invention. 
     FIG. 3 is a sectional view of an embodiment of the nozzle assembly, suction chamber and target tube of the invention. 
     FIG. 4A is a sectional view of 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. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     The embodiment of FIG. 1 illustrates barge  100  for dredging solid materials from a water source, such as a lake or river. Barge  100  is equipped with cantilever system  101  to raise and lower suction pipe  102  into the water source. Suction pipe  102  is connected to jet pump  107 . 
     Discharge pipe  103  feeds water or other fluid pumped by 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 pump housing  105 . Discharge pipe  103  also feeds jet nozzle  106  which is connected to discharge pipe  103  before jet pump  107  and suction pipe  102 . 
     Although suction pipe  102  is shown in FIG. 1 as defining an angled suction inlet  109  to jet pump  107  before becoming parallel to discharge pipe  103 , suction pipe  102  can be 45° or any angle greater than 0° and less than 180° to discharge pipe  103  for the entire length of suction pipe  102 . Centrifugal pump  108  can optionally be placed downstream of jet pump  107 . Centrifugal pump  108  is typically a centrifugal pump but can be any pumping means. 
     The depiction of the invention for use in the dredging industry as reflected in FIG. 1 is only one example application for illustrative purposes. The jet pump  107  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. 
     FIG. 2 illustrates a preferred embodiment of jet pump  107 . Jet pump  107  includes nozzle assembly  307  (shown on FIG. 3) comprising fluid nozzle  201 , air injection nozzle  202  and 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. Air hose  204  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 pipe  103 , fluid nozzle  201 , and air injection nozzle  202  into suction chamber  205 . In suction chamber  205 , the fluid combines with material entering from suction pipe  102 , and the combined stream enters target tube  206 . The combined stream then passes through target tube  206  into outlet pipe  207 . 
     In a preferred embodiment a first end  106   a  of jet nozzle  106  extends from discharge 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 a second end  106   b  opposite the first end  106   a  connected to discharge pipe  103 . Venturi  208  is equipped with air hose  210  to allow entry of atmospheric air through an air hole  209  defined by the second end  106   b  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 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. 
     Constricted throat  301  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. In a preferred embodiment, nozzle housing  203  has eight ¾ inch holes equal distance around the circumference of nozzle housing  203 . 
     Air injection nozzle  202  has drilled air hole  304 . Although air injection nozzle  202  is depicted with one air hole  304 , those skilled in the art would know that multiple air holes can be provided. In a preferred embodiment depicted in FIG. 6, air injection nozzle  202  has eight ½ inch holes equal distance around the circumference of air injection nozzle  202 . 
     When air injection nozzle  202  and fluid nozzle  201  are assembled, air hole  304  can align with air intake  211 . Alignment however is not necessary, as fluid nozzle  201  and air injection nozzle  202  should be constructed with a minimal clearance to allow air to surround the fluid jet as it passes through constricted throat  301  into nozzle opening  202 . In a preferred embodiment, the clearance is 0.01 inches. 
     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 atmosphere 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. 
     It is believed that entry of atmospheric air into air gap  302  creates an air 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. 4A and 4B, 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  401 . 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 vaccum in air gap  30 L was 18-22 inches of Hg. 
     Air bearing  401  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 end  102   b  of 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 a preferred embodiment, 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  102   a  of suction pipe  102 . The suction effect increases the overall quantity of material driven by pump  104 . The following table illustrates the ratio of pumped liquid entering fluid nozzle  201  to total material exiting target tube  206 : 
     
       
         
               
               
               
               
               
               
             
               
               
               
               
               
               
             
           
               
                   
               
               
                 Pump 
                 Vacuum 
                 Liquid 
                 Liquid 
                   
                   
               
               
                 Discharge 
                 Measured 
                 Exit 
                 Inlet 
                   
                 Discharge 
               
               
                 Pressure 
                 In Air 
                 Power 
                 Fluid Nozzle 
                 Suction 
                 Pressure Exit 
               
               
                 (psi) 
                 Gap (Hg) 
                 (GPM) 
                 (GPM) 
                 Ratio 
                 Tube (psi) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 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 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 flowrate or discharge pressure. 
     Target tube  206  is constructed as a detachable wear plate. 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 a support in the form of 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  306   a  and from outlet pipe  207  on the other end  306   b  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 pump  108 , as shown in FIG. 1, can be placed downstream of target tube  206  despite the introduction of atmospheric air before nozzle opening  203 . No cavitation occurs in centrifugal 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 2 6×12 reducing flanges, each connected to one end of 12¾ pipe 10 inches long. Interior target tube wear plate  305  (as shown in FIG. 3) is composed of non-abrasive disposable material such as 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. Constricted throat  301  measures 3 inches in diameter on outer edge  702 . 
     Air injection nozzle  202  is 12 and ⅞ 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 and {fraction (3/16)} inches, then drops radially to a diameter of 2 and ½ inches for the remainder of the length. 
     Air hole  303  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 measures 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 one or more, preferably eight, 1″ NPT connections in air intake  211 . 
     While it is understood that the jet pump described herein is characterized by the entry of atmospheric air and a detachable 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. Such adaptions and modifications are intended to be comprehended within the range of equivalents of disclosed embodiments. Terminology used herein is for the purpose of description and not limitation. 
     The 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. The invention can also be used in closed loop dewatering applications to remove excess water or moisture from material. 
     There are, of course, other alternate embodiments which are obvious from the foregoing descriptions of the invention, which are intended to be included within the scope of the invention, as defined by the following claims.