Fluid sprinkling – spraying – and diffusing – Combining of separately supplied fluids – Including additional dispersing plate or obstruction in...
Reexamination Certificate
2001-03-05
2003-04-15
Douglas, Lisa A. (Department: 1764)
Fluid sprinkling, spraying, and diffusing
Combining of separately supplied fluids
Including additional dispersing plate or obstruction in...
C239S434000
Reexamination Certificate
active
06547164
ABSTRACT:
The present invention relates to a vapor-liquid ejector with a nozzle that is removable (or dismountable).
BACKGROUND OF THE INVENTION
This type of device is known per se. It enables a liquid to be entrained by means of a driving fluid: namely the vapor. Said vapor passes through the nozzle of the device which transforms its pressure into speed. The nozzle is usually of the “supersonic” type having a converging-diverging profile which serves to increase outlet speed compared with that which would be obtained using a converging-only nozzle. Optimum efficiency is obtained by bringing the pressure of the vapor close to the suction pressure of the liquid. On coming into contact with the driven liquid, the vapor condenses very quickly, but not instantly. There generally remains a “dart” of vapor in the form of a converging cone at the outlet from the nozzle.
The driving fluid is generally steam, but there is no a priori reason why some other kind of vapor should not be used, providing its physical conditions are suitable and it does not pollute the driven liquid.
Whatever the kind of vapor used, the ejector nozzle which is engaged removably in the body of said ejector is raised to a relatively high temperature because of the flow of said vapor through the nozzle, thus making it a part which is sensitive to attack by corrosion. This problem is particularly applicable to the portion of the nozzle which is in contact with the driven liquid.
In any event, the problem of corrosion is critical in the clearance that must be present in order to enable the removable nozzle to be engaged in the body of the ejector, which clearance is accessible to the driven liquid and, with reference to said liquid, constitutes a kind of dead zone.
Crevice corrosion inevitably develops in said clearance.
OBJECTS AND SUMMARY OF THE INVENTION
The present invention has been developed with reference to this problem of corrosion in the structure of vapor-liquid ejectors having removable nozzles.
To make the invention easier to describe and also easier to understand, the present description begins with reference to the accompanying
FIG. 1
by describing the structure of prior art removable-nozzle vapor-liquid ejectors. On sight of said structure, the above-mentioned corrosion problem can easily be understood. With respect to said problem, the present invention proposes an improvement to the structure of such prior art removable-nozzle vapor-liquid ejectors.
As shown in section in
FIG. 1
, the body
10
of such a prior art ejector
1
(and more precisely a recess
14
in said body
10
) contains a nozzle
2
which is removably engaged therein. Said body
10
is provided:
with a first duct
11
for feeding said nozzle
2
with vapor V, i.e. the driving fluid; and
with a second duct
12
downstream from the first duct
11
along the axis of said nozzle
2
and relative to the flow direction of said vapor V, for the purpose of introducing the driven liquid L into said body
10
.
Said nozzle
2
is positioned in stable manner in the recess
14
of said body
10
, coming into abutment against an internal shoulder
13
of said body
10
. A shoulder
3
of said nozzle
2
co-operates with said shoulder
13
.
Sealing means
9
are located at the facing surfaces of said shoulders
3
and
13
, i.e. the surfaces
3
′ and
13
′, which sealing means are for preventing the liquid L that is driven through the duct
12
from rising further upstream.
The sealing means
9
define two zones
14
′ and
14
″ in the recess
14
of said body
10
of the ejector
1
:
an upstream zone
14
′ which, in theory, is not accessible to the liquid L; and
a downstream zone
14
″ which is accessible to the liquid L, which zone begins with an interstitial volume
v
which is generally annular insofar as said recess
14
and said nozzle
2
(over a fraction of its length) are generally cylindrical in shape. This volume corresponds to clearance enabling the nozzle
2
to be assembled in the recess
14
in the body
10
of the ejector
1
. This clearance is provided between the outside surface
4
of the body of the nozzle
2
where it extends downstream from the shoulder
3
of said body of said nozzle
2
, and the surface
13
″ of the inner shoulder
13
of the body
10
of the ejector
1
which faces said outer surface
4
of the body of said nozzle
2
. The volume extends along the axis of said nozzle
2
over a length that goes from said shoulder
3
of said body of the nozzle
2
(the sealing means
9
) to level with the location where said driven liquid L is introduced via the second duct
12
into the downstream zone
14
″ of the recess
14
in the body
10
of the ejector
1
(the arrival zone of said liquid L).
On observing FIG.
1
and on reading the above, the person skilled in the art will already have understood that the above-mentioned corrosion is critical in said interstitial volume
v
where the driven liquid L is heated by coming into contact with the outer surface
4
of the nozzle
2
and where it tends to stagnate. In prior art ejector structures, this volume
v
generally has a thickness
e
that is constant and equal to about 0.2 millimeters (mm).
In the invention, it is proposed to modify the internal structure of such ejectors in order to minimize corrosion problems in said volume
v
.
It has been found that two types of modification are necessary to obtain the desired effect (to transform said volume
v
from a dead zone to a genuinely dynamic zone):
said volume
v
must be enlarged; and
means must act to ensure that said enlarged volume
v
is swept by (non-stagnant) liquid;
surprisingly, it has been found that these modifications do not significantly degrade the hydraulic performance of the ejector in question.
The main object of the present invention is thus to provide a novel removable-nozzle vapor-liquid ejector of the type shown in accompanying FIG.
1
and modified in the manner outlined above.
Said novel ejectors thus comprise in conventional manner a body having a recess that receives a removable nozzle, said body of said ejector presenting:
a first duct for feeding said nozzle with vapor;
a second duct downstream from said first duct along the axis of said nozzle relative to the flow direction of said vapor and serving to introduce the driven liquid into said recess of said body; and
between said first and second ducts, an internal shoulder against which a shoulder of the body of said nozzle comes into abutment, sealing means being interposed between the facing surfaces of said two shoulders to prevent the driven liquid rising upstream from said sealing means; a (generally annular) interstitial volume inherent to said engagement then existing between the outer surface of the body of said nozzle where it extends downstream from the shoulder of said body of said nozzle and the surface of the internal shoulder of the body of the ejector facing said outer surface of the body of said nozzle, said (generally annular) interstitial volume extending along the axis of said nozzle over a length that goes from the shoulder of said body of said nozzle to the level where the driven liquid is introduced into said body of said ejector via the second duct and giving said driven liquid access to said sealing means.
In novel manner, said ejectors of the present invention present within the above-specified conventional structure, the following two characteristics:
said (generally annular) interstitial volume has a thickness of at least 2 mm over its entire length developed along the axis of the nozzle; and
on its outside surface, said nozzle has means facing said second duct that are suitable for directing at least a fraction of the driven liquid flow towards the sealing means via said (generally annular) interstitial volume.
These two characteristics in combination make it possible to achieve the desired result, i.e. to minimize corrosion in said (generally annular) interstitial volume by ensuring that the liquid genuinely flows within said volume with this flow of said liquid genera
Bretault Philippe
Michel Didier
Miquel Pierre
Poncelet François
Cohen & Pontani, Lieberman & Pavane
Compagnie Generale des Matieres Nucleaires
Douglas Lisa A.
LandOfFree
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