Pumps – Processes – Of pumping one fluid by contact or entrainment with another
Reexamination Certificate
1999-09-27
2001-06-26
Freay, Charles G. (Department: 3746)
Pumps
Processes
Of pumping one fluid by contact or entrainment with another
C417S053000, C417S151000, C417S196000, C417S198000
Reexamination Certificate
active
06250888
ABSTRACT:
BACKGROUND
The invention pertains to the field of jet technology, primarily to pumping-ejection units for producing a vacuum and for compression of gaseous mediums.
An operating process of a pumping ejector system is known, which consists of delivery of a liquid medium under pressure into the nozzle of a liquid-gas ejector by a pump, forming of a liquid jet at the outlet of the nozzle and evacuation of a gaseous medium by this jet, mixing of the liquid and the gaseous mediums and obtaining a gas-liquid stream, discharge of the gas-liquid 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 introduces a pumping ejector system having a pump and a liquid-gas ejector, wherein the pump is connected by its discharge side to the ejector's nozzle, the ejector's inlet of the passive gaseous medium is connected to a source of the evacuated medium and the ejector's outlet is connected to drainage.
The described operating process and system for its embodiment have not found wide industrial application because discharge of the gas-liquid mixture into [the] drainage often results in environmental pollution and the system's operation requires high consumption of a liquid medium. The latter makes the system 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 liquid medium from a separator into the nozzle, or several nozzles, of a liquid-gas ejector by a pump, evacuation of a gaseous medium by a jet of the liquid motive medium, mixing of the mediums in the ejector and forming of a gas-liquid flow with simultaneous compression of the gaseous medium (see RU, patent, 2091117, cl. B 01 D Mar. 10, 1997).
The same RU patent 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 this operational 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 utilisation of gravitational forces in the delivery pipe connecting the ejector and separator.
But together with this positive effect such a design also has a significant imperfection concerned with the fact, that a high-altitude position of the jet apparatus and a long delivery pipe provokes a jump of the gas-liquid flow's speed in the delivery pipe. As a result, speed of the gas-liquid flow at the separator's 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's 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's altitude above the separator.
The solution of above mentioned problem is provided by an operating process of a pumping-ejector unit, which includes delivery of a liquid medium from a separator to the nozzle, or several nozzles, of a liquid-gas ejector by a pump, evacuation of a gaseous medium by a jet of the liquid motive medium flowing from the ejector's nozzle, mixing of the mediums in the ejector and forming of a gas-liquid flow with the simultaneous compression of the gaseous medium, feeding of the gas-liquid flow from the ejector into a chamber for supersonic flow conversion, where the gas-liquid flow is exposed to abrupt expansion in a shaped canal in order to reduce the density of the gas-liquid flow down to a predetermined value and to provide a flow speed which is not lower than the sonic speed in this gas-liquid flow, subsequent passing of the flow through another shaped canal where it is slowed down to a predetermined speed by means of a pressure jump, and feeding of the decelerated gas-liquid flow into the separator, where compressed gas is separated from the liquid motive medium.
In order to achieve the design speed of the flow at the separator's inlet the unit can be furnished with several chambers for supersonic flow conversion providing several cycles of flow expansion and subsequent deceleration to a subsonic speed through a pressure jump. Thus gradual braking of the flow is ensured. Subject to design of the separator it is expedient to slow the gas-liquid flow down to 4.6 to 450 m/sec.
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 by its suction side to the separator, and a liquid-gas ejector, whose liquid inlet is connected to the discharge side of the pump and gas inlet is connected to a source of an evacuated gaseous medium, is furnished additionally with a chamber for supersonic flow conversion. An inlet of this chamber is connected to the ejector's outlet, the chamber's outlet is connected to the separator. The chamber constitutes a shaped canal diverging stepwise in the flow direction.
The Inlet of the chamber for supersonic flow conversion can be fastened to the outlet section of the ejector's mixing chamber. The outlet of the chamber for supersonic flow conversion can be fastened to the separator's inlet.
There is another variant of the design of the pumping-ejector unit, comprising a separator, a pump connected by its suction side to the separator, and a liquid-gas ejector, whose liquid inlet is connected to the discharge side of the pump and gas inlet is connected to a source of an evacuated gaseous medium. In this variant the unit is furnished with not less than one chamber for supersonic flow conversion, the inlet of the chamber (or chambers) for supersonic flow conversion is connected to the ejector's outlet, and the outlet of the chamber (or chambers) is connected to the separator. In this case the ejector has a multi-nozzle design and comprises a motive liquid distribution chamber with active nozzles at its outlet, a receiving chamber and mixing chambers coaxial to each nozzle.
Each mixing chamber can be furnished with its own chamber for supersonic flow conversion, the multi-nozzle ejector can be furnished with a discharge chamber installed at the outlet end of the mixing chambers, and in this case the chamber for supersonic flow conversion can be fastened directly to the outlet of the discharge chamber.
The chamber for supersonic flow conversion can be composed of two stepwise conjugated portions, with a ratio of the cross-sectional area of the downstream portion to the cross-sectional area of the upstream portion can range from 1.05 to 10, the length of the downstream duct can not be more than {square root over (12 +L S)}, where S is the cross-sectional area of the upstream duct.
A pipe connected to the outlet of the chamber for supersonic flow conversion can have a uniform section, or it can be convergent with the taper angle up to 26° or divergent with the taper angle up to 5-60°. With regard to the shape of the cross-sections of the chamber for supersonic flow conversion and pipes, their shape has no vital importance and can be for example circular, oval, polyhedral etc.
Experimental research has shown, that backpressure at the ejector's outlet exerts significant influence on the liquid-gas ejector's performance. Therefore it was necessary to ensure deceleration of the flow prior to its entry into the separator without a significant increase of the
Doubinski Anatoli M.
Popov Serguei A.
Freay Charles G.
Gray Michael K.
Oathout Mark A.
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