Ventilation – Having protecting air current – Including plural – layered currents
Patent
1997-08-01
1999-08-10
Joyce, Harold
Ventilation
Having protecting air current
Including plural, layered currents
454191, F24F 900
Patent
active
059349921
DESCRIPTION:
BRIEF SUMMARY
The present invention has for its object a method and a device for confinement of an atmosphere in a space communicating with the outside thanks to at least one opening; a gas curtain being generated at the level of said opening.
This method and device are advantageously employed for the confinement of a special atmosphere in a space for continuously processing objects or articles fed therethrough. According to the prior art, to Applicants' knowledge, particularly when such processing employs explosive, toxic and/or contaminating substances, they are employed discontinuously. Thus, when it is desired to process articles in an atmosphere presenting particular characteristics which must be maintained between precise values (characteristics of temperature, hygrometry, gaseous composition, concentration of liquid or solid particles in suspension . . . ), one generally proceeds in spaces provided at the entrance and at the exit with chambers with tight double doors. Under such conditions: matter and energy, proportional to the volume of said chambers . . .
According to the present invention, an improvement to the conventional technology of the confinement of a space by a double-jet gas curtain is proposed more precisely. Said technology is illustrated in particular in Patent Applications FR-A-2 530 163 (confinement of a polluted space) and FR-A-2 652 520 (confinement of a "clean" space). According to the said technology, the double-jet gas curtains are used for separating two spaces containing atmospheres of different characteristics. Such gas curtains are intended to stop any solid or liquid particles in suspension in the atmospheres of the separated spaces but must, however, allow the passage of macroscopic objects passing therethrough without exchange between said separate atmospheres.
Such gas curtains comprise a slow jet of which the point (the inner cone: potential flowing zone) ensures the dynamic separation of the atmospheres and a fast jet which stabilizes and rigidifies said slow jet.
Incidentally, it is recalled here that the flow of a jet of gas, in any section thereof, is generally the sum of the initial flow of gas blown in and of the flow taken by suction in the gaseous environment outside the jet. This second flow constitutes the induced flowrate of said jet.
Opposite the jet emission nozzles, there is generally found a suction orifice which collects the gas blown as well as a fraction of the separate atmospheres which are mixed with said blown gas in the induction zone. The gases collected by such a suction orifice are generally processed before recycling or rejection in the environment. The matter and energy lost by the suction flow are considered as necessary and/or negligible vis-a-vis the result sought. However, the suction orifice does not systematically take up the double jet. The nozzles for emission of the fast jet and of the slow jet are supplied with non-polluted gas. They generally present a slight inclination, towards the outside of the opening of the space to be confined, such that in the hypothesis of confinement of a "clean" zone to be protected from the outside pollution (context of document FR-A-2 652 520)--that face of the fast jet located towards the space to be confined is virtually parallel to the plane of said opening. Said "clean" space to be confined is supplied by a flow of non-polluted gas, called clean gas stream, slightly greater than the flowrate induced by the inner face of said fast jet (located towards the space to be confined); the excess flowrate with respect to the latter ensuring a slight leakage rate which prevents the penetration of the fast jet in said space to be confined. In any case, according to the prior art, the nozzles of the gas curtain never inject gas directly in the space to be confined.
Conventionally, when it is question of protecting an environment from "pollution" (the "pollution" being located inside or outside the space to be confined), the fast jet is always located towards the non-"polluted" side.
The double-jet gas curtain is generally
REFERENCES:
patent: 4576613 (1986-03-01), Miline
patent: 5145459 (1992-09-01), Meline et al.
patent: 5312294 (1994-05-01), Meline
patent: 5336085 (1994-09-01), Sharma et al.
Meline Fran.cedilla.ois
Sohier Laurent
Boles Derek S.
Joyce Harold
Societe Generale Pour Les Techniques Nouvelles Sgn.
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