Patent Application
20150285271
The present invention relates to a jet pump and in particular, but not exclusively, to a jet pump for use in the oil and gas industries.
Jet pumps or eductors are passive devices that use energy from a high pressure (HP) fluid source to boost the pressure of a low pressure (LP) fluid. The terms jet pump, eductor, ejector and gas jet compressor are used in various industries and refer to the same general type of device. The HP and LP fluids may each consist of liquids, gases or a mixture of liquids and gases.
LP fluid from a LP source passes through a LP inlet 12 and is introduced into the jet pump at the nozzle discharge zone 10, where it is entrained in the flow of fluid emerging from the nozzle 8. The mixture of fluids then passes through a mixing tube 14 where momentum and energy are exchanged between the fluids. The mixture finally passes through an expanding diffuser 16 where the velocity of flow normalises and pressure recovery takes place. The pressure at the outlet 18 of the jet pump will be at an intermediate value between the pressures of the HP and LP fluids and the inlets 4, 12. In some jet pumps the nozzle 8 and the mixing tube/diffuser 14, 16 comprise replaceable components that are mounted within a housing 20. Jet pumps have been used successfully in a variety of applications onshore or near the bottom of oil or gas wells. In such situations the HP fluid may be gas or a high pressure liquid such as oil or water. The LP fluid could be gas, or liquid (oil and/or water), or a mixture of gas and liquid.
In some applications, particularly when the HP fluid is a liquid and the LP fluid is predominantly a gas, complete mixing of the HP and LP fluids may not take place. This can adversely affect the operational efficiency of the jet pump.
It is an object of the present invention to provide a jet pump that mitigates one or more of the aforesaid disadvantages.
According to one aspect of the present invention there is provided a jet pump including a HP inlet vent, a nozzle connected to the HP inlet vent via a HP fluid conduit and configured to discharge a first fluid flowing through the HP inlet into a nozzle discharge zone, a LP inlet vent, a LP fluid conduit connected to the LP inlet vent and configured to discharge a second fluid flowing through the LP inlet vent into the nozzle discharge zone, a mixing tube downstream of the nozzle discharge zone for mixing the first and second fluids and an outlet vent downstream of the mixing tube for discharging a mixture of the first and second fluids from the jet pump, wherein the jet pump includes a spinner mechanism upstream of the nozzle discharge zone for causing spinning rotation of at least one of the first and second fluids about a longitudinal axis of the nozzle.
We have found that by spinning at least one of the first and second fluids about a longitudinal axis of the nozzle, the mixing of the fluids in the mixing tube can be significantly improved. This applies in all situations, including even a situation where the HP first fluid is a liquid and the LP second fluid is predominantly a gas. Complete mixing of the HP and LP fluids can thus be ensured, thereby significantly improving the operational efficiency of the jet pump.
Advantageously, the spinner mechanism includes a LP inlet chamber connected to receive the second fluid from the LP fluid conduit, the LP inlet chamber comprising a fluid passageway that extends circumferentially around the nozzle to cause rotation of the second fluid around the longitudinal axis of the nozzle.
The LP inlet chamber may include a curved wall that extends at least partly around the nozzle. The LP inlet chamber may be substantially involute in shape, being defined by a curved wall that has a decreasing radius of curvature from its upstream end to its downstream end. Alternatively, the LP inlet chamber may be substantially cylindrical in shape.
Advantageously, the LP inlet chamber has a tangential inlet port connected to the LP inlet vent.
Advantageously, the LP inlet chamber has an annular outlet port configured to discharge the second fluid into the nozzle discharge zone.
Advantageously, the spinner mechanism includes a spinner device located within the HP fluid conduit, which is configured to cause rotation of the first fluid around the longitudinal axis of the nozzle. A spinner device may also be provided within the LP inlet chamber.
The spinner device preferably includes at least one helical blade configured to cause rotation of the first fluid as it flows through the HP fluid conduit.
Certain embodiments of the invention will now be described by way of example with reference to the accompanying drawings, in which:
A low pressure second fluid from a LP source passes through an LP inlet 112 and is introduced into an involute inlet chamber 114 that encircles the inlet tube 106 and is positioned just upstream of the nozzle 108 and the low pressure nozzle discharge zone 110. The involute chamber 114 is defined by a curved wall 116 of decreasing radius that curves around the nozzle 108. The involute chamber 114 is defined between the curved wall 116 and the circular wall of the inlet tube 106. This chamber 114 has a cross-sectional area that decreases from the inlet end to the outlet end of the chamber.
The LP second fluid flowing through the LP inlet 112 into the involute inlet chamber 114 is guided by the curved wall 116 so that it rotates around the inlet tube 106 as shown in
The rotating second fluid exits the involute inlet chamber 114 through an annular gap 117 that surrounds the inlet tube 106. The rotating LP second fluid is then combined in the nozzle discharge zone 110 with the first fluid emerging from the nozzle 108 and the first and second fluids are mixed within the mixing tube 118 downstream of the nozzle 108. The spinning motion of the LP second fluid causes the first and second fluids to mix thoroughly within the mixing tube 118. The mixture of fluids then passes through an expanding diffuser 120 where the velocity of the flow normalises as pressure recovery takes place. Finally, the mixture of fluids exits the jet pump 102 at outlet 122. The pressure of the fluid mixture at the outlet 122 will be at an intermediate value between the pressures of the first and second fluids at the HP and LP inlets 104, 112.
In this embodiment the inlet tube 106 and the mixing tube/diffuser 118, 120 are replaceable components that are mounted within a housing 124. Alternatively, the nozzle 108, the mixing tube 118 and the diffuser 120 may be permanently mounted within or formed integrally with the housing 124.
The second jet pump shown in
In the embodiment of
The two fluids are mixed within the mixing tube 118 and the mixture then flows through the diffuser 120 towards the outlet 122. As before, the mixture of fluids emerging from the outlet 122 will have a pressure that is intermediate between the pressures of the first and second fluids at the HP and LP inlets 104, 112.
Optionally, the HP inlet tube 106 may include a mechanical static spinner device 130 located within the HP inlet tube 106 upstream of the nozzle 108, as shown in
| Number | Date | Country | Kind |
|---|---|---|---|
| 1406059.4 | Apr 2014 | GB | national |
This application claims priority under 35 USC 119 to British application no. GB 1406059.4 filed Apr. 4, 2014, and the disclosure of said British application is hereby incorporated by reference in its entirety.
