Note: Descriptions are shown in the official language in which they were submitted.
The present invention relates generally to a high
ratio pressure reducing valve and in particular provides a valve
structure wherein a fluid flow restrictor is mounted outside the
valve body such that the use of high strength, heavy wall con-
struction is required only in the areas of the valve forming
the annulus around the valve stem and the fluid inlet port.
In the handling of high pressure fluid flow it is often
necessary to provide an economical, safe means for permitting
a high pressure drop in the fluid flow. Typically, high ratio
pressure reductions are necessary in the operation of power-
operated relief valves wherein high pressure steam, for example,
from a boiler system is vented to a low pressure condenser or to
the atmosphere. Heretofore known means for venting high pressure
fluid to the atmosphere or to a low pressure outlet include
arrangements such as valves with low pressure drops and a silen-
cer or noise attenuating devices connected to the outlets thereof.
Valves provided with a series of downstream pressure-reducing
orifice plates have also been used, as well as valve structures
incorporating fluid flow restrictor devices.
While the above-mentioned prior art devices have been
somewhat effective in their intended use, there are drawbacks
associated with each one. For example, the state of the art
for fluid flow restrictor devices (e.g., of the stacked disc
type) is such that these devices are superior in noise attenu-
ation and fluid energy dissipation than the silencers attachable
to standard valves. However, the fluid flow restrictor devices
are generally mounted within a web portion of a vaive body and
disposed between the inlet and outlet portions of the body.
In the high pressure drop application contemplated by the present
inven,tion, an eight-inch inlet pipe would require a valve body
with an outlet having a diameter of between 20 to 40 inches.
Such a large diameter outlet requirement would result in a very
bulky, expensive valve structure. And, of course, utilizing a
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standard valve-silencer combination necessarily sacrifices the
more favorable operating characteristics of a fluid flow re-
strictor device.
In one prior art proposal, the Self U.S. Patent No.
4,068,683, for example, a stacked plate fluid flow restric~or is
mounted on a plate integrally formed with a fluid inlet pipe.
The r~ostrictor stack includes a central, cylindrical inlet
chamber which overlies the open end of the inlet pipe whereby
fluid flows from the pipe into and through the restrictor to
the a~mosphere. An axially movable valve plug is received within
the chamber such that the stack may be partially exposed to fluid
flow or the flow may be interrupted completely. While the Self
arrangement utilizes a fluid flow restrictor without the need of
a large valve body, the high pressure steam on the upstream side
of the device exerts considerable pressure on the valve plug
tending to place high forces on the plug stem. To ameliorate the
stem force problem~ the Self proposal provides axially extending
passageways in the valve plug, whereby high pressure steam may
flow above the plug and flow restrictor to balance the forces
acting on the valve plug and stem. However, this places a high
pressure force above the restrictor, requiring a heavy, rigid
construction for the components fastening the flow restrictor to
the mounting plate, thereby increasing the weight, cost and
complexity of the device.
It is a primary objective of the present invention to
provide a valve device incorporating a fluid flow restrictor
with a balanced valve plug and without the requirement of heavy
duty const~uc~ion in areas other than the high pressure fluid
inlet portions of the device. In its broadest aspects, the valve
of the present învention comprises a high pressure fluid inlet
means with an open end and means to attach a fluid flow restrictor
device to the inlet means whereby the inlet portion of the re-
strictor device is in fluid communication with the open end of
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the high pressuxe inlet. An axially movable valve plug is
received within the flow restrictor device and is movable by
an operating stem which is connected to the plug and extends
therefrom on the upstream, high pressure side of the valve. A
valve seat is formed intermediate the fluid flow restrictor
and the open end of the inlet means, whereby the valve plug
can mate therewith to close the valve. When the stem is oper-
ated to lift the plug from the valve seat, high pressure fluid
from the inlet means will flow directly into and through the
flow restrictor device such that the device will subject the
fluid flow to a controlled, gradual energy dissipation to
atmospheric pressures. The fluid may then be exhausted directly
from the restrictor device to the atmosphere or to a low pressure
component.
Pursuant to an important aspect of the invention, a
balancing element is associated with the valve stem and includes
a portion having a cross-sectional area in an opposed, spaced
relation to the upstream, high pressure side of the valve plug.
The cross-sectional areas of each of the balancing element and
the upstream side of the valve plug are matched whereby high
pressure fluid from the inlet means will act evenly on each of
the surfaces to thereby substantially eliminate unbalanced fluid
forces acting upon the stem, valve plug or areas outside the
fluid flow restrictor or high pressure inlet means.
To considerable advantage, the valve of the present
invention effectively confines high pressure forces to within
the inlet means, eIiminating the need for a bulky, heavy con-
struction for the remaining components of the valve. For ex-
ample, the above-described valve structure will greatly simplify
the means for connecting the fluid flow restrictor to the inlet
pipe. It will not now be necessary to provide heavy reinforcing
structures to hold the restrictor against the high pressures
of the upstream fluid. Moreover~ the balanced valve plug will
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facilitate smooth, easy operation of the valve stem to provide
a dependable, convenient valve action~ The output of the fluid
flow restrictor device may be opened directly to the atmosphere
thereby providing a high ratio pressure reducing valve utilizing
the advanced technology of a fluid flow restrictor device in a
streamline structure. 3
For a more complete understanding of the above and t
other features and advantages of the invention, reference should
be made to the following detailed description of a preferred
embodiment of the invention and to the accompanying drawings.
Fig. 1 is a side cross-sectional view of a high ratio,
pressure-reducing valve built in accordance with the principles
of the invention.
Fig. 2 is a cross-sectional view of the fluid flow
restrictor portion of the new valvè, taken generally along
line 2-2 of Fig. 1.
Referring now to the drawings and initially to Fig. 1
thereof, the reference numeral 10 designates a high pressure
fluid flow inlet. Integral therewith is a valve body 11 in-
cluding opposed, spaced passageway openings 12, 13. The open-
ings 12, 13 are each in communication with the passage 14 of
the inlet 10 and are disposed in a generally perpendicular
relation to the central~ longitudinal axis of the inlet 10.
In the illustrated form of the invention, the passage-
way opening 12 is ~ormed to include concentric, circular lands
15, 16. A hollow cylindrical sleeve 17 ~rovided with a circular,
radially-extending flange 18 is snugly received within the
passageway opening 12 such that the circular flange 18 rests
on the land 16 and the internal wall of the sleeve 17 forms a
continuation of the sides of the opening 12. Moreover, an
integral cylindrical extension 19 of the sleeve 17 extends
into contacting relation with a portion of the land 15. Packing
material 20 is tightly received between the land 15, flange 18
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and extension 19 to provide a leak-tight seal between the out-
side of the sleeve 17 and the interior of the passageway opening
12
A tapered surface 21 is formed along the inner peri-
meter of the open top of the sleeve 17 to define a valve seat.:
The portions of the valve body extending from the land 16 and
surrounding the sleeve 17 are formed to provide an internal
thread 24. In this manner, the arrangement of passageway
opening 12 and sleeve 17 described above provides a fluid out-
let passage 23 from the valve inlet 10 to the atmosphere 22.
The threaded section 24 is in a concentric, spaced relation
to the sleeve 17 to accommodate simplified attachment of a
fluid flow restrictor device, as will appear.
In Fig. 1, the reference numeral 25 generally desig-
nates a fluid flow restrictor, including a central fluid inlet
chamber 26, arranged to overlie the sleeve 17 such that the
chamber 26 is in fluid communication with the fluid passage 23.
To advantage, the fluid flow restrictor 25 comprises a series
of close-fitting, concentric cylinders 27 - 32 which are rigidly
2Q fastened together, as for example, by welded joints. Each of
the cylinders 27 ~ 32 includes a plurality of radially disposed
openings 33 spaced across the surface thereof and extending
through the particular cylinder with a uniform diameter.
As can be clearly seen in Fig. 2, the concentric
cyLinders 27 - 32 are arranged and configured whereby each open-
ing 33 of each cylinder overlaps at least one opening 33 of
each contiguous cylinder ~o form restricting orifices between
the overlapping openings 33, Moreover, each opening 33 is suffi-
ciently large to provide an expansion chamber for fluid flowing
therethrough. Accordingly, as will be described in greater
detail hereinafter, high pressure fluid, for example steam,
flowing through the valve will flow through the passage 23,
into the input chamber 26, and then subdivide into separate
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streams passing through the openings 33. The individual streams
will each undergo a gradual, controlled energy dissipation by
passing through the series of expansion chambers and restricting
orifices defined by the overlapping openings 33.
To advantage, the diameter of the openings 33 may be
arranged to progressively increase in the downstream direction
to accommodate expansion of compressible fluids, such as steam.
Typically, the dimensions of each opening 33, the degree of over-
lap therebetween and the number of cylinders may be predetermined
with great mathematical accuracy, so that the pressure of the
steam passing from the outermost, downstream cylinder 32 of the
fluid flow restrictor 25 will have been sufficiently reduced for
safe, direct exhaust of the steam to the atmosphere 22.
For a more detailed description of a fluid flow restric-
tor of the type described above, reference should be made to Cana-
dian Application Serial No. 308,301 filed July 27, 1978. Of course,
it should be noted that the present invention is not limited to
use in connection with a fluid flow restrictor of the type dis-
closed in the aforementioned Canadian application. However, it is
considered preferable to utilize such a restrictor herein.
Referring once again to Fig. 1, the inner two cylinders
27, 28 of the restrictor 25 are formed to extend beyond the lower
ends of the remaining cylinders 29-32 to provide a cylindrical
skirt extension. The innermost cylinder 27 includes a recess 34
formed in its inner surface and the cylinder 28 is ~rovided with
- a threaded outer surface 35. The cylinders 27, 28 are received
within the space between the sleeve 17 and the threaded section 24
such that the restrictor is threadedly engaged with the thread
surface 24 and the recess 34 of the restrictor cylinder 27 is
closely ~eceived over the sleeve 17. In this manner, the restric-
tor 25 is securely fastened to the valve body and the input chamber
26 of the restrictor is in direct fluid communication with the
flow passage 23, as discussed above.
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A valve plug 36 is slidably received within the
restrictor inlet chamber 26 and includes a tapered surface 37
arranged for a mating relation with the valve seat 21 of the
sleeve 17. When the valve plug 36 is in its lower~ost position,
as illustrated in Fig. 1, the valve will be closed and no steam ,-
will be able to escape from the pipe 10. As the plug 36 is
displaced axially to, for example, the dished-line position
indicated in Fig. 1, steam may flow from the pipe 10 through the
passage 23 and into the inlet chamber 26. The greater the
displacement of the plug 36 from the valve seat 21, the greater
the number of openings 33 that will be exposed to steam. Con-
sequently, movement of the plug 36 will control the rate of steam
escape to the atmosphere. A valve stem 38 is formed integral
with the plug 36 to control the axial movement of the plug 36
within the inlet chamber 26, as will appear.
In accordance with one of the features of the invention,
a cylindrical balancing element 39 is slidably received within
the passageway 13 such that the upper surface 40 thereof is in a
spaced, confronting relation to the lower surface ~1 of the valve
plug. The valve stem 38 is provided with a threaded end section
43 which is received within a threaded opening 43 formed at the
center of the upper su-rface 40 of the balancing element 39. The
opposite end of the balancing element 39 is connected by a nut
and threaded surface arrangement to a control rod 44 which is
associated with a suitable actuator apparatus (not shown) to
provide controlled, simultaneous, axial displacement for the
valve plug 36 and the balancing element 39. To advantage, the
opening 13 includes a section 45 of increased diameter wh~reby
packing material 46 may be disposéd between the balanclng ele-
ment 39 and the sides of the opening 13 to form a leak-tight
seal therebetween. The packing 46 is held in place by a flanged
collar 47 which is received over ~he balancing element 39 and
secured to the end section 11 by a plurality of bolts 48.
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Steam ~low from the interior 14 of the valve inlet 10
enters into each of the passageway openings 12, 13 and exerts a
fluid pressure on the surfaces 40, 41. The pressure acting on
the surface 40 is opposite to the pressure acting on the sur-
face 41, whereby the two pressure effects counteract each other.
In accordance with one form of the invention, the cross-sectional
areas of these surfaces 40, 41 are closely matched in value so
that there is a complete offsetting of fluid pressure forces
and the valve plug 36 is perfectly balanced. Accordingly, oper-
ation of the valve will be unaffected by unbalanced pressures.In another fcrm of the invention (not specifically illustrated),
the cross-sectional area of the surface 40 is formed to be
slightly larger than the cross-sectional area of the surface 41.
This arrangement will result in a slight pressure unbalance
tending to urge the valve plug 36 toward the valve seat 21,
thereby providing a tight valve shut-off.
Even re significantly, the balancing feature of the
invention confines all high pressure fluids to within the valve
body areas 10, 11. When the valve plug 36 is lifted from the
valve seat 21, the high pressure fluid will flow directly into
the fluid flow restrictor 25 for a controlled energy dissipation.
In accordance with another feature of the invention,
the threaded connection 42, 43 between the valve stem 38 and
balancing element 39 facilitates easy assembly of the device of
the present invention. The valve plug 36 is received through the
inlet chamber 26 of flow restrictor 25 and the balancing element
39 is received through the passageway 13. The two elements are
then fastened together by rotat~ng e~ther or both of the plug 36
and/or balancing element 39 to threadedly engage the end 43
of the val~e stem 38 within the threaded opening 42 of the
balancing element 39. With such an arrangement, it is not nec-
essary for the balancing element 39 to have a slightly smaller
diameter than the fluid passage 23 in order to clear the valve
seat 21 during asse~bly. This would be the case if the balancing
element were formed integral with the valve plug 36 and valve
stem 38 since such an arrangement would require the balancing
ele~ent to be passed through the input chamber 26 and fluid
passage 23 to assemble the device. With the two-part construc-
tion, the cross-sectional areas of the opposed surfaces 40, 41
may be precisely matched or the surface 40 may even be formed
to be slightly larger in cross-sectional area than the surface 41.
Accordingly, the two-part construction for the balan-
cing element 39 and valve plug 36 permits a perfect balancing
or slight unbalancing for a tight sealing of the valve plug
while providing a straightforward assembly procedure, Opera-
tion of the valve will be smooth and with minimal unbalanced
pressures on the stem 38 and valve plug 36.
To advantage, a protective screen 49 may be mounted
on the valve body by a plurality of bolts 50 to surround the
fluid flow restrictor 25. The screen places a protective barrier
around the restrictor 25 and channels the exhausted steam
upwardly and away from the valve apparatus.
Instead of using the screen 49, provisions may be
made to connect the valve body to the inlet of a low pressure
device such as a condenser.
Thus, the present invention provides a highly advan-
tageous high ratio pressure reducing valve. The fluid flow
restrictor efficiently and safely dissipates the fluid energy
of ~he steam, while the balancing means effectively confines
the high pressure effects of the steam to within the valve
body 10, 11. In accordance with the disclosure, straightforward
and simplified means are utilized to fasten the restrictor to
the pipe and a balanced or slightly unbalanced plug insures a
smooth, reliable valve action with a tight valve shut-off.
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