GB1572990A - Jet pumps - Google Patents

Description

(54) IMPROVEMENTS RELATING TO JET PUMPS (71) We, ROBOJBT LIMITED Of 140141 Temple Chambers, Temple Avenue, London EC4Y OHE, a British company, do hereby declare the invention for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a jet pump comprising a housing, which has an inlet portion for the entry of the substance to be pumped and defines a mixing chamber, a jet nozzle for producing a high-velocity jet of motive fluid, and a mixing nozzle for the outlet of the motive fluid and said substance, the nozzles having a common axis and extending into the mixing chamber. Jet pumps are known and are widely used for pumping fluids, i.e. gases or liquids, or solids composed of small discrete particles.

Jet pumps for handling solids have been used for many years in applications such as dredging and handling marine cargoes and tank residues Known jet pumps have various disadvantages known to persons skilled in the art. The pumps are prone to frequent blockage, and usually have a rectangular or square hopper leading to the mixing chamber which is not suitable for optimum suction flow or for the creation of conditions in which minimum hydrodynamic energy losses are achieved. Some pumps use as means for reducing the blockage wash-down nozzles which cause merely dilution of solid/fluid mixtures and are not positioned or constructed so as to establish optimum fluid boundary layer regimes leading to minimum solid/fluid mixture shear rates at the hopper walls.

The aim of the invention is to avoid or at least to mitigate the above disadvantages of known jet pumps by a suitable design of the pump housing, including the mixing chambed design, which may be associated with hydrodynamically constructed boundary jet nozzles such that minimum net positive suction head (NPSH) is required by the pump, resulting in improved performance and suction characteristics of the pump, particularly when handling solids.

In addition the improved design is believed to lead to reduced blockage formation in the entry to the mixing nozzle caused in known pumps by solids collecting in low velocity areas created by unequal flow and turbulence.

The invention provides a jet pump comprising a housing, which has an inlet portion for the entry of the substance to be pumped and defines a mixing chamber, a jet nozzle for producing a high-velocity jet of a motive fluid, and a mixing nozzle for the outlet of the motive fluid and said substance, the nozzles having a common axis and extending into the mixing chamber, the pump including substantially helical paths leading from the inlet portion to the mixing chamber.

Preferably the housing is substantially circular in cross-section and its crosssectional area decreases from the inlet portion to the mixing chamber.

In a preferred embodiment the pump comprises two set paths which are substantially in the form of two separate helices, the diameter of which increases in the direction away from the inlet portion, the paths ending in the mixing chamber at opposite sides of the said common axis.

The pump may comprise at least one boundary jet nozzle having an outlet slit which terminates in the surface of one of the paths and delivers thereto a stream of fluid.

The invention will now be described, by way of 'example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a section along line A-A in Figure 2, Figure 2 is a plan view with the screen removed, Figure 3 is a section along line B-B in Figure 2, Figure 4 is a section along line D-O-D in Figure 2, Figure 5 is a section along line C-O-C in Figure 2, Figure 6 is a section along line E-O-E in Figure 2 with items 8 and 14 removed, Figure 7 is a view in the direction of the arrow X in Figure 2, Figure 8 is a detail showing one embodiment of a boundary jet nozzle, and Figure 9 is a detail showing another embodiment of a boundary jet nozle.

The illustrated pump comprises a generally cup-shaped housing 1 which is substantially frusto-conical and circular in cross-section, and has at the large-diameter end an inlet portion provided with castellations 2 and at the small-diameter end a bottom 3. The term "bottom" is used for simplicity and is not intended to imply that the pump operates only in the position shown in Figure 1. The pump can operate in any position, including the "upside down" position in which the bottom 3 is at the top and the inlet portion lies e.g.

on a floor or a bottom of a tank. In fact the castellations 2 are made to enable the pump to operate in the latter position in which it works in a manner of a vacuum cleaner.

The inlet portion contains a screen 4 including a ring 5 carrying e.g. a circular sieve or a perforated plate. The ring 5 is fixed in the inlet portion by a suitable locking means (not shown), e.g. of the bayonet type, so that the screen 4 can be easily and quickly removed and another screen, including a sieve of a desired mesh number, substituted therefor.

The pump includes a high-pressure jet nozzle 8 and a mixing nozzle 9 which extend partially into a mixing chamber defined by the housing 1 in the vicinity of the nozzles, are co-axial and are positioned a small distance from the bottom 3. The common axis of the two nozzles 8, 9 does not intersect the vertical axis of the housing 1. The jet nozzle 8 is axially adjustable relative to the mixing nozzle 9. When the pump is in the position shown in Figure 1 the part of the housing 1 between the castellations 2 and the mixing chamber acts as a hopper.

Inside the housing 1 are provided two peripheral paths, namely an outer path 6 and an inner path 7. Both the paths 6, 7 start at the inlet portion of the housing 1 at and above the nozzle 9 and extend to the bottom 3 substantially in the form of a double helix of a decreasing diameter.

As is apparent from Figure 2 the outer path 6 is longer than the inner path 7, and the paths 6, 7 end at opposite sides of the nozzle 8. The paths 6, 7 are not symmetrical, although each of them is wound substantially about a vertical axis intersecting the common axis of the nozzles 8, 9.

The pump further includes an inlet branch 10A for high-pressure motive fluid which communicates via an arcuate conduit 11 with the jet nozzle 8 which extends through the conduit 11 and is provided with one or more inlet openings 12 within the conduit. The conduit 11 is situated within the housing 1 and is integral therewith without communicating with the interior of the housing 1. The inlet branch 10A may be provided with a control valve 13.

Alternatively, the jet nozzle 8 may be supplied with the motive fluid through an opening (not shown) at its back, which in the illustrated embodiment is closed by a cap 14.

The outlet end of the mixing nozzle 9 passes through an outlet branch lOB which ends in a discharge connector 15 which is adapted for the connection of a pipe or hose. The inlet branch 10A and the outlet branch 10B are interconnected by a stiffening rib 16 and the discharge connection 15 has means 17 for the connection of a conduit for delivering to the discharge a suitable fluid, e.g. water or compressed air, for its dilution.

The whole housing 1 including the paths 6, 7, the conduit 11 and the branches lOA, 10B are cast in one piece.

The pump may also have a plurality of boundary jet nozzles 1 8A which in the illustrated embodiment extend through the conduit 11. Each boundary jet nozle 1 8A has an inlet opening 19A within the conduit 11 and an outlet slit 20 which terminates in the surface of the path 6 or 7, each nozzle 18A being controllable by a needle valve 21. In the illustrated example one nozzle 18A is at the start of the two paths 6, 7, one is near the end of the path 6 and one is near the end of the path 7.

Each nozzle 18A delivers a stream of the high-pressure fluid from the conduit 11 to the surface of the path with which it is associated. This reduces or prevents formation of boundary layers of the substance being pumped flowing on the paths 6, 7.

Alternatively each nozzle 18B may be supplied with a suitable fluid (either the same or other than that in the conduit 11) through an inlet opening 19B at its back.

The pump according to the invention works on the same principle as other jet pumps. In the pump a high-pressure stream of motive fluid (indicated by white arrows), e.g. air or water is directed through the jet nozzle 8 which produces a high-velocity jet which creates a low pressure area in the mixing chamber thus inducing suction of the substance to be pumped (indicated by black arrows), e.g. a fluid (such as water, sewage, crude oil or oily wastes) or powdery, granulate or particulate solid (such as sand, gravel, coal, iron ore or grain), or any mixture thereof, through the screen 4 in to the mixing chamber.

One of the advantages of the pump is that the housing is so designed that the entry of the substance to be pumped in to the mixing nozzle entry is guided and constrained to the helical paths 6 and 7. Due to the described design of these two paths 6 and 7 equal proportions of the substance being pumped are conveyed to both sides of the jet nozzle 8 and delivered with a fluid pattern which converges to the common axis of the nozzles 8 and 9.

The helical paths 6 and 7 ensure that velocities of the substance flowing along these paths until final mixing with the highvelocity motive fluid in the mixing nozzle 9 are such that gradual acceleration occurs thereby ensuring optimum conditions for minimum hydrodynamic energy loss and also promoting a flow pattern such that low velocity areas are minimised, transport velocity maintained and settlement of solids reduced.

Where high viscosity fluids are pumped or where the admixture of solids or fluids in to the substance being pumped increases its viscosity or produces high fluid shearrates at the boundary layers, thus reducing the suction performance of the pump, improvements in or restoration to the desired suction performance can be obtained by the use of the boundary jet nozzles 1 8A or 18B which supply to the paths 6 and 7 clean low viscosity fluid, which may be the motive fluid taken from the conduit 11.

Another of the advantages of the invention is that the various elements of the jet pump, including the paths 6, 7, the branches 10A, lOB and the conduit 11, can be integrated with the housing 1.

The pump can be advantageously used in constricted and inaccessible spaces and in hazardous conditions where robot operation is necessary.

The arrangement of the inlet branch 10A and the outlet branch lOB at the same side of the housing 1 in close proximity thereto and in parallel arrangement allow the conveying and discharging pipes or hoses to be positioned at minimum spacing from each other and allow access to containers and the like through apertures of small dimensions such as openings in ships or tanks.

WHAT WE CLAIM IS: 1. A jet pump comprising a housing, which has an inlet portion for the entry of the substance to be pumped and defines a mixing chamber, a jet nozzle for producing a high-velocity jet of a motive fluid, and a mixing nozzle for the outlet of the motive fluid and said substance, the nozzles having a common axis and extending into the mixing chamber, the pump including substantially helical paths leading from the inlet portion to the mixing chamber.

2. A jet pump according to Claim 1 wherein the housing is substantially circular in cross-section and its cross-sectional area decreases from the inlet portion to the mixing chamber.

3. A jet pump according to Claim 1 or 2 comprising two said paths which are substantially in the form of two separate helices the diameter of which decreases in the direction away from the inlet portion, the paths ending in the mixing chamber at opposite sides of the said common axis.

4. A jet pump according to Claim 1, 2 or 3 comprising at least one boundary jet nozzle having an outlet slit which terminates in the surface of one of the paths and delivers thereto a stream of fluid.

5. A jet pump according to Claim 4 wherein the or each boundary jet nozzle is controlled by a needle valve.

6. A jet pump according to Claim 4 or 5 including a conduit for supplying the jet nozzle with the motive fluid which is associated with the housing.

7. A jet pump according to Claim 6 wherein at least one of the said boundary jet nozzles extends through said conduit.

8. A jet pump according to Claim 7 wherein the or each boundary jet nozzle passing through the said conduit is supplied with the fluid from said conduit.

9. A jet pump according to Claim 6, 7 or 8 including an inlet branch communicating with the said conduit and an outlet branch communicating with the said mixing nozzle, the two branches being attached to the housing close to each other and being substantially parallel.

10. A jet pump according to Claim 9 wherein the housing, the paths, the conduit and the two branches are integral.

11. A jet pump according to any one of the preceding claims wherein the inlet portion includes castellations.

12. A jet pump according to Claim 9, 10 or 11 wherein a control valve is attached to the inlet of the inlet branch and the jet nozzle is at its back provided with an inlet opening which is closed by a cap.

13. A jet pump according to Claim 9, 10 or 11 wherein the inlet of the inlet branch is closed by a cap and the jet nozzle is at its back provided with an inlet opening to which is attached a control valve through which the jet nozzle is supplied with the motive fluid.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (14)

**WARNING** start of CLMS field may overlap end of DESC **. jet which creates a low pressure area in the mixing chamber thus inducing suction of the substance to be pumped (indicated by black arrows), e.g. a fluid (such as water, sewage, crude oil or oily wastes) or powdery, granulate or particulate solid (such as sand, gravel, coal, iron ore or grain), or any mixture thereof, through the screen 4 in to the mixing chamber. One of the advantages of the pump is that the housing is so designed that the entry of the substance to be pumped in to the mixing nozzle entry is guided and constrained to the helical paths 6 and 7. Due to the described design of these two paths 6 and 7 equal proportions of the substance being pumped are conveyed to both sides of the jet nozzle 8 and delivered with a fluid pattern which converges to the common axis of the nozzles 8 and 9. The helical paths 6 and 7 ensure that velocities of the substance flowing along these paths until final mixing with the highvelocity motive fluid in the mixing nozzle 9 are such that gradual acceleration occurs thereby ensuring optimum conditions for minimum hydrodynamic energy loss and also promoting a flow pattern such that low velocity areas are minimised, transport velocity maintained and settlement of solids reduced. Where high viscosity fluids are pumped or where the admixture of solids or fluids in to the substance being pumped increases its viscosity or produces high fluid shearrates at the boundary layers, thus reducing the suction performance of the pump, improvements in or restoration to the desired suction performance can be obtained by the use of the boundary jet nozzles 1 8A or 18B which supply to the paths 6 and 7 clean low viscosity fluid, which may be the motive fluid taken from the conduit 11. Another of the advantages of the invention is that the various elements of the jet pump, including the paths 6, 7, the branches 10A, lOB and the conduit 11, can be integrated with the housing 1. The pump can be advantageously used in constricted and inaccessible spaces and in hazardous conditions where robot operation is necessary. The arrangement of the inlet branch 10A and the outlet branch lOB at the same side of the housing 1 in close proximity thereto and in parallel arrangement allow the conveying and discharging pipes or hoses to be positioned at minimum spacing from each other and allow access to containers and the like through apertures of small dimensions such as openings in ships or tanks. WHAT WE CLAIM IS:

1. A jet pump comprising a housing, which has an inlet portion for the entry of the substance to be pumped and defines a mixing chamber, a jet nozzle for producing a high-velocity jet of a motive fluid, and a mixing nozzle for the outlet of the motive fluid and said substance, the nozzles having a common axis and extending into the mixing chamber, the pump including substantially helical paths leading from the inlet portion to the mixing chamber.

2. A jet pump according to Claim 1 wherein the housing is substantially circular in cross-section and its cross-sectional area decreases from the inlet portion to the mixing chamber.

3. A jet pump according to Claim 1 or 2 comprising two said paths which are substantially in the form of two separate helices the diameter of which decreases in the direction away from the inlet portion, the paths ending in the mixing chamber at opposite sides of the said common axis.

4. A jet pump according to Claim 1, 2 or 3 comprising at least one boundary jet nozzle having an outlet slit which terminates in the surface of one of the paths and delivers thereto a stream of fluid.

5. A jet pump according to Claim 4 wherein the or each boundary jet nozzle is controlled by a needle valve.

6. A jet pump according to Claim 4 or 5 including a conduit for supplying the jet nozzle with the motive fluid which is associated with the housing.

7. A jet pump according to Claim 6 wherein at least one of the said boundary jet nozzles extends through said conduit.

8. A jet pump according to Claim 7 wherein the or each boundary jet nozzle passing through the said conduit is supplied with the fluid from said conduit.

9. A jet pump according to Claim 6, 7 or 8 including an inlet branch communicating with the said conduit and an outlet branch communicating with the said mixing nozzle, the two branches being attached to the housing close to each other and being substantially parallel.

10. A jet pump according to Claim 9 wherein the housing, the paths, the conduit and the two branches are integral.

11. A jet pump according to any one of the preceding claims wherein the inlet portion includes castellations.

12. A jet pump according to Claim 9, 10 or 11 wherein a control valve is attached to the inlet of the inlet branch and the jet nozzle is at its back provided with an inlet opening which is closed by a cap.

13. A jet pump according to Claim 9, 10 or 11 wherein the inlet of the inlet branch is closed by a cap and the jet nozzle is at its back provided with an inlet opening to which is attached a control valve through which the jet nozzle is supplied with the motive fluid.

14. A jet pump according to Claim 1

constructed, arranged and adapted to operate substantialy as herein described with reference to, and as shown in, the accompanying drawings.