Pumps – One fluid pumped by contact or entrainment with another – Jet pump with motive fluid generating pump
Reexamination Certificate
1999-12-27
2001-11-06
Tyler, Cheryl J. (Department: 3746)
Pumps
One fluid pumped by contact or entrainment with another
Jet pump with motive fluid generating pump
C417S087000, C417S151000, C417S158000
Reexamination Certificate
active
06312229
ABSTRACT:
BACKGROUND
The present invention pertains to the field of jet technology, primarily to pumping-ejector units for producing a vacuum and for compression of gaseous mediums.
An operating process of a pumping-ejector system is known, which consists of feeding a liquid medium under pressure into a nozzle of a liquid-gas ejector by a pump, forming of a liquid jet at the outlet of the nozzle, evacuation of a gaseous medium by this jet, mixing of the liquid medium and the gaseous medium, forming a gas-liquid stream and subsequent discharge of the stream from the ejector into drainage (see “Jet Apparatuses”, book of E. Y. Sokolov, N. M. Zinger, “Energia” Publishing house, Moscow, 1970, pages 214-215).
The same book also introduces a pumping-ejector system including a pump and a liquid-gas ejector, where the pump is connected through its discharge side to the ejector nozzle, the passive gaseous medium inlet of the ejector is connected to a source of an evacuated medium and the ejector outlet is connected to drainage.
The described operating process and system for its embodiment have not experienced wide industrial application because discharge of the gas-liquid mixture into sewage often results in environmental pollution. In addition, operation of the system requires the high consumption of a liquid medium. The latter makes such systems economically unattractive.
The closest analogue of the operating process introduced by the present invention is an operating process of a pumping-ejector unit, which includes delivery of a motive liquid medium from a separator to at least one nozzle of a liquid-gas ejector by a pump, evacuating a gaseous medium by a jet of the motive medium, mixing of the mediums and forming of a gas-liquid flow in the ejector with simultaneous compression of the gaseous medium (see RU, patent, 2091117, cl. B 01 D 3/10, 1997).
The same RU patent No. 2091117 also describes a pumping-ejector unit for embodiment of the process. It includes a separator, a pump and a liquid-gas ejector. The liquid inlet of the ejector is connected to the discharge side of the pump and the gas inlet of the ejector is connected to a source of an evacuated gaseous medium.
With the operating process and related pumping-ejector unit it is possible to reduce energy consumption because the liquid-gas ejector is placed at a height of 5 to 35 meters above the separator and thus provides utilization of gravitational force in the delivery pipe connecting the ejector and the separator.
But together with this positive effect such a design also has a significant imperfection concerned with the fact, that the high altitude position of the jet apparatus and the long delivery pipe provoke a jump in the gas-liquid flow speed in the delivery pipe. As a result, the speed of the gas-liquid flow at the separator inlet, where a hydroseal is made, can reach hundreds of meters per second. Therefore there is a necessity to reinforce those elements of the separator which react to the increased load generated by the high-speed flow. This leads to an increase in the separator dimensions and specific consumption of materials.
SUMMARY OF THE INVENTION
The present invention is aimed at improving reliability of a pumping-ejector unit, which can be achieved by adjusting the flow speed at the inlet of a separator regardless of spatial positioning of a liquid-gas ejector (horizontal or vertical) and regardless of the ejector altitude above the separator.
The solution of the above mentioned problem is provided by an operating process of a pumping-ejector unit, which includes delivery of a liquid motive medium from a separator to at least one nozzle of a liquid-gas ejector by a pump, evacuating a gaseous medium by a jet of the motive medium flowing from the ejector nozzle(s), mixing of the mediums in the ejector and forming a gas-liquid flow with simultaneous compression of the gaseous medium, feeding the gas-liquid flow from the ejector into a hydrodynamic device for adjusting the flow speed, deceleration of the gas-liquid flow in the hydrodynamic device to a subsonic speed due to a controllable enlargement of a flow-through canal of the device and subsequent feeding of the decelerated gas-liquid flow into the separator, where compressed gas is separated from the liquid motive medium.
With regard to the apparatus as the subject-matter of the invention, the mentioned technical problem is solved as follows: a pumping-ejector unit including a separator, a pump connected through its suction side to the separator, and a liquid-gas ejector, whose liquid inlet is connected to the discharge side of the pump and whose gas inlet is connected to a source of an evacuated gaseous medium, is furnished with a hydrodynamic device for adjusting the flow speed. The device can be composed of one or several portions joined in series, where each portion represents a canal diverging in the flow direction. An inlet of the hydrodynamic device is connected to the ejector outlet, an outlet of the device is connected to the separator. The surface area of the outlet cross-section of each divergent canal of the device is from 4.0 to 50 times larger than the surface area of its inlet cross-section. The length of each divergent canal of the device is not less than 1.36 {square root over (S)}, where S is the surface area of the outlet cross-section of this divergent canal.
The inlet of the hydrodynamic device for adjusting the flow speed can be fastened directly to the outlet section of the ejector, the outlet of the hydrodynamic device can be fastened directly to the separator inlet.
The pipes connecting the inlet and the outlet of the hydrodynamic device (for adjusting the flow speed) to the ejector outlet and the separator inlet (if any) can have a uniform section, or they can be convergent with a taper angle of up to 26° or divergent with a taper angle of up to 5-6°. With regard to the shape of the cross-sections of the divergent canals of the hydrodynamic device and the cross-sections of the pipes, their shape has no vital importance and can be, for example, circular, oval, polyhedral etc.
It has been discovered that backpressure at the outlet of a liquid-gas ejector exerts a significant influence on the performance of the ejector. Therefore it is necessary to ensure deceleration of the flow prior to its entry into the separator without a significant increase in backpressure.
It was found that the most successful way to achieve same is to use energy of the gas-liquid flow itself for the deceleration of the flow and to make the deceleration system easy to control. Additionally, it is essential to impart a feedback feature to the deceleration system, i.e. to provide the ability to adjust the operating mode of the ejector by varying pressure, for example, in the separator. It was also found to be important to provide such conditions under which the flow passes from the outlet of the liquid-gas ejector to the inlet of the separator at a subsonic speed.
In a number of cases, for example when the ejector is installed vertically at a relatively high altitude above the separator, it is expedient to compose the hydrodynamic device for adjusting the flow speed with several divergent canals arranged one after another in series. It was discovered that, in such cases, the built-up hydrodynamic device operates better than a hydrodynamic device composed of a single canal with a significant enlargement, which can not provide deceleration of the flow to the permissible speed ranging from 4.6 to 450 m/sec. In connection with this, it is not expedient to make the divergent canal or canals with a ratio of the surface area of the outlet cross-section to the surface area of the inlet cross-section more than 50 and less than 4.0. The length of each canal must not be less than 1.36 {square root over (S)}, where S is the surface area of the outlet cross-section of the canal.
As to the location of the divergent canals of the hydrodynamic device, it is advisable to place the canals evenly between the ejector outlet and the separator inlet. But when the ejector is installed at a l
Oathout Mark A.
Petroukhine Evgueni D.
Tyler Cheryl J.
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