Note: Descriptions are shown in the official language in which they were submitted.
This inventio~ relates ~o a valve, It relates more
particularly to an erosion-resistant valve. for use in severe
throttling service ~pplications.
s ~b~
The valves with which we are concerned here are used to
thro~tle the flow of fluids maintained at very high tempera ures
(e.y. 850O F) and pre~sures te.g. 2000 psi) and containing
abrasive particles, a coal ash slurry for example. In these
difficult service applications, the valve par~s suffer a
considerable amount of erosion and wear~ The conventional way to
maximize the service life of such valves is by fabricating those
valve par~s which are particularly prone to erosion of. very
: abrasive resistant materials and specially profiling and
: ~ ~15 s~reamlining them to achieve smooth fluid flow around those
parts~ ~owever, such parts made of those hard materials are
.
: extremely difficult to fabricate and are therefore quite costly.
As a practical matter, then, when designing such valves there is
inevitably a compromise made between valve cost and service life.
: 20
In~ lo~
Thus it is an objeet of the present invention to provide a
valve which is particularly resistant to erosion.
Another object of the inven~ion is to provide a throttlinq
25 valve for handl ing abrasive fluids at high temperatures and
pressures and which has a relatively long service 1 if e.
Another object of the invention is to provide a valve of
~7Z~ ~
this type whose parts can be replaced ~uickly and easily in the
event that becomes nece~sary.
Still another objeet of the invention is to provide such a
valve which is relatively economical ~o mak* and maintain.
Other objects will, in part, be obvious and will, in part,
appear hereinafter.
The invention ac~ordingly comprises the fea~ures of
construction, combination of elements, and arrangement of parts
which wlll be exemplified in the following detailed description,
lQ and the scope of the invention will be indicated in the claims.
Briefly, my valve comprises a housing which defines a
relatively large, generally cylindrical chamber. An inlet port
is formed in the housing and communicating therewith is a tubular
throttlirlg tube which pro~ects into ~he chamber more or less
}5 coaxiall~y therewith. Tha~ throttling tube, which is more or less
centered in the chamber, is formed as a replaceable part. The
outlet ~ort is located in the cylindrical wall of ~he housing and
it is positioned appreciably radially outboard of the inner end
of the throttling tube.
Th~ vaIv~ closure member comprise an elongated throttling
:~: plug or rod dimensioned to be snugly received in the mouth of ~he
throttling tube with minimum clearance between the two. The plug
is mounted inside the chamber directly opposite the mouth of the
throttl in~ tube and is movable between an extended or closed
25 position wherein i~ projects slightly into ~he ~u~e to achieve
maximum throttling effect and a retracted or open position
wherein it is spaced from the mouth of the tube so that it
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~ t7~
throttles the fluid to a minimum extent~ Ths plug is moved to
any setting between these two positions by a more or less
conventional actuator mounted to the valve housing and controlled
manually or by suitable elec~ric, pneumatic or hydraulic motive
means. It should be understood at ~his point that throttling
valves generally are never fully Glosed or fully open in the
sense that the plug does not at all obs~ruct the incoming fluid.
Rather, the valve is arranged to always throttle the fluid flow
to some extent between maxlmum and minimum values. Therefore,
the use of the words "open" and "closed" when referring to plug
position should be viewed in this context.
With the valve connected to a sour~e of fluid and the
throttling plug in its open position~ fluid is free to flow
through the inlet port and thro~tling tube into the valve ~hamber
lS and thence to the valve outlet port~ To minimize erosion and
wear due to the incoming fluid, the replaceable throttling tube
may be constructed of a single piece of erosion-resistant
material such as ~ool steel, cemented carbides or ~eramics, for
example. Alterna~ively, it can be provided with a very hard
,
inser~ of such ma~erial at its inner surface which is subjected
to the most wear. Likewise, the throttling plug can be made of
: the same erosion-resis~an~ material or it can be pla~ed or
cladded so that it is abraded ~o a minimum extent by the incoming
fluid. Even though the plug and tube are composed oiL such hard
material, being simple, e.g. cylindrical, shapes, they are
relatively easy to fabricate.
The walls of the valve chamber are spaced an aDpreciable
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~ 7~
distance from the inner end or mouth of the throttling tube 9
Fur~hermore, ~he fluid being throttled, suffers an appreciable
pressure drop when entering that large chamber. Therefore, ~he
walls of the valv~ chamber suffer minimum wear. ~owever, in very
5 severe service applications, a replac:eable ~all liner or baffle
may be posi~ioned inside the valve chamber to protect those walls
as will be described later.
To close the valve, the ac~uator is caused to advance ~he
plug ~oward ~he mou~h of the throl:tling tu~e~ When the plug is
lO even with or projects slightly into the mouth of the tube,
maximum throttling is achieved. P~ny residual flow through the
: valve may be shut off by a separate, conventional shut-off valve.
Dur ing normal use of the present valve, the mating sur faces
of the throttling plug and tube are inevi~ably abraded and worn
15 by the fluid . ~owever, in the present Yalve ~ this wear is
compensated for because the valve actuator is designed to advance
the plug further and further toward the ~hrottling tube as 'che
mating surfaces erode away. In other words, the plug is made
overly long and the actuator is arranged to feed more and more of
the plug length into the tube so that unabraded surfaces of the
plug and tube are brought into mating engayement to achieve
maximum thro~tling effect.
Further, the actuator can be arranged to rotate the pl ug as
it is being advanced in order to minimize the likelihood of
2~ localized erosion of the mating plug and tube parts. Also in
- some severe service applications, the plug may be provided with
an axial passage through which oil or other fluid under high
r~ ~ 7~6
pressure is forced to form a film over the end face of the plu~
so as to effectively prevent the abrasive particles in the
incoming fluid from actually touching the plug surfaces at the
point of maximum throttling.
Eventually, with repeated valve actuations, the ef~ective
length of the plug will be eroded away and that part will have to
be replaced. Likewise, the removable throttling tube may have to
be rep~aced. However, this is accomplished simply by removing
the valve housing bonnet to gain access to the valve chamber.
10` Then the plug is detached from the actuator and replaced with a
new one. Also if necessary, the worn tube can be removed from
the valve housing wall and substituted for by a fresh on As
soon as the housing bonnet is replaced, the valve can be placed
in service again. Thus, the aforesaid replacement of parts can
be a~complished quickly and easily so that valve downtime is kept
to a minimum.
A~cordingly, the present valve can tolerate a considerable
amount of parts wear while preserving the effectiveness of ~che
valve. Therefore the time between required valve shutdowns is
2~ relatively long. ~alve wear for the most part is confined to a
few parts which are relatively inexpensive to make and are easily
replaceable so that, when it does become necessary to service the
valve, this can be done in a minimum amount of time and at
minimum cost. Therefore, the present valve should find wide
application in the control of the flow o~ abrasive fluids and in
other heavy industrial applications presenting severe throttling
problems.
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, ~ ~ J"l.t7~G1~
For a fuller understanding of the nature and objects of the
invention, reerence should be had to the following detailed
description, taken in connec~ion with the accompanying drawing,
in which.
FIG. 1 is a sectional view with parts in elevation of a
throttling valve embodying ~he principles of this invention with
the valve shown in its open position
FIG. 2 is a ~ectional view along line 2-2 of FIG. 1, and
FIG. 3 is an enlarged fragmenta~y se~tional view showing the
valve in its closed position.
Referring now ~o FIG. 1 of the drawing, my valve shown
15 generally at lO includes a relatively large, generally
cylindrical housing 12 having a bottom wall 12a and a generally
cylindrical side wall 12b which together define a relatively
larse generally eylindrical chamber 13 inside the valve. The
valve inlet port 14 is ormed in ~he housing bottom wall 12a and
is provided with an external flange 14a. The valve outlet port 16
is formed in the housing side wall 12b and is also flanged at
15a. Us~ally the outlet port has a larger diameter than the
inlet port. Circular arrays of openings 18 and 22 are provided
in flanges 14a and 16a to facilitate connecting the valve to
. upstream and downstream piping. Secured to the top of housing
side wall 12b is a bonnet 26 which supports the valve actuator
shown generally at 28.
^ 1~'7Z~
~ e~erring to FIGS. 1 and 2~ a throttling tube shown
generally at 36 is removably secured to the housing bottom wall
l~a inside chamber 13 and coaxially with ~he inlet port 14. The
throttling tube includes a main tubular section 36a whose mouth
or end 36b pro~ects a substantial distance into housing chamber
13 and a redu~ed diameter neck portion 36c which seats in the
housing bottom wall 12a. A stepped bore 4~ is form~d in ~he
housing bo tom wall 12a to snugly receive the necked down
~hrottling tube. The upper inside wall of that bore is threaded
10at 44 to mate with corresponding external thread5 46 inscribed on
the ou~side of tube section 36a at the bottom thereof. Also a
suitable annular seal 48 surrounds the tube neck portion 36c to
provide a fluid~tight seal between the throttling tube 36 and the
housing bottom wall 12a.
15The throttling tube 36 may be a single unitary piece made of
an abrasive~resistant material such as tool steel or a carbide.
More preferably and as shown in FIG. 1, the tube may be composed
of a main body 50 ~ade ~f a sof~-er material such as steel and a
cylindrical refrac~ory inner liner 52 that forms the surfaces
subjected to the most wear when the valve is in use.
Referring particularly to FIG. 1, lhe illustrated valve
closure member comprises simply a cylindrical thro~tling plug or
rod 54 which is disposed opposite and coaxially with the
throttling sleeve 36. The diameter of the plug is slightly less
25 than that of the tube mouth 36b and its end 54a is more or less
flat.
The plug 54 ext@nds up through a cylindrical bushing 58
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6~
positicned in a control passage 62 in bonnet ?6 havin~ a neck
26a. The bonnet seats against the top o~ housing side wall 12b
and is ~ecured thereto by a circular array of threaded studs 66
projecting up from the wall 12b through openings 68 near the edge
of the bonnet. Nuts 72 turned down onto the ends of the studs
clamp the bonnet to the housing flange and an annular seal 74 a~
the underside of the bonnet prevents fluid leakage between the
bonnet and the housing.
An upper sec~ion 62a of ~he bonnet passage ~2 inside neck
lO 26a is enlarged to receive a packinq ring 78. The ring 78 is
compressed between the plug 54 and the wall of passage 62a by a
packing follower 82 which is engaged around plug 54 and
positioned in passage section 62a o~ the upper end of bonnet neck
: 26a thereby forming a fluid-ti~ht rotary and sliding seal between
: 15 the plug 54 and bonnet 26. Overlying the follower a2 is a ring
84. Threaded studs 86 projecting up rom neck 26a extend through
openings in the ring and receive nuts 88 to clamp the ring to the
bonnet neck 26a.
Mounted to the top of bonnet neck 26a is an enclosure 92
~ having an opening 93 in its bottom wall which receives the neck.
The en~losure is secured to neck 26a by a nut 94 turned down onto
exterior threads 95 on the neck. Plug 54 extends through bonnet
26 into enclosure 92 and its upper end 54b is threaded and pinned
into a ~oupling 98 formed a~ ~he lower end of a shaft 102. Shaft
25 . 102 extends uæ throu~h the top wall of enclosure 92 into a second
enclosure 104 where it is connected by a rotary coupling 106,
which permits shaft 102 to rotate with respect to piston rod 108,
_ g _
to one end of a pis~on rod 108 whos~ other end terminates in a
piston 108a. Enclosure 104 constitutes a hydraulic or pneumatic
piston cylinder having a long stroke capability. A compression
spring 112 underlying pis~on 108a and reacting against an
internal flange 104a in enclo~ure 104 biases the piston toward
its re~racted or raised position. Fluid under pressure
introduced into enclosure 104 above piston 108a via a conduit 114
causes ~he piston to move plu~ 54 toward tube 36.
Referring to FIG. 1~ when the valve 10 is conne~ted in the
line, with the plug 54 in its open position as shown in that
figure, fluid flows through the valve inlet port 14 into chamber
13 by way ~f the throttling ~ube 36. Then~e, ~he fluid leav~s
the chamber through the outlet port 16. To achieve maximum
throttling of the fluid fed ~o ~he valve, the a~uator 28
advances the plug 54 toward the thrvttling sleeve 36. ~he plug
is advanced by an amount sufficien~ to posi~ion i~s end 54a more
or less even with or slightly inside the mouth 36b of the
: ~ throttling tube to ~he po~i~ion illustrated in FIG. 3. Typically
: the stroke of the plug 54 between its fully open and closed
positions is about one-fourth of the diameter of the bore or
orifice in the thro~tling tube 36.
When the plug is in the closed position, the flow of fluid
into the chamber is throttled to a maximum extent. With this.
general type of valve, further penetration of the plug into the
tube does not result in appreciable further stoppage of fluid
flow. Rather, complete stoppage of the fluid (if this is
desired) is achieved by means of a completely separate shut-off
-- 10 --
~L~'7~
valve tnot shown) positioned in the pipe in line with the valve
10~ Of course, intermediate throttling values are achieved by
positioning the plug end 54a at appropriate distances from the
mouth of tube 36.
As the valve performs its throttling function, erosion will
occur primarily at the lower end of plug 54 and a~ the upper
inner surface portion of the throttling tube 36 ~or more
particularly its liner 52). Consequently, with a ~onventisnal
fixed-stroke type valve, after such wear, the valve may not
1~ perform its throttling function properly. With the present
valve, however, such erosion is ~ompensated ~or by making the
plug several times longer than its normal operating stroke and
controlling actua~or 28 so as to progressively shift the
operating stroke of valve stem 58 toward tube 36. In other
words, for maximum throttling, plug 54 is advanced toward the
throttling sleeve 36 until a substantially unabraded, full
diameter end segment of the plug intercepts a non-eroded segment
of the tube liner 52. For example in a valve with a tube 36
having a two inch bore, the dis~ance traveled by plug 54 between
its open and closed positions might be on the order of one-half
inch. Consequently, the plug would be made, say, one inch long 50
that as the end 54a of the plug erodes away, the plug can be
~dvanced over a period of time, further and further toward the
throttlin~ tube 36 much like a pencil into a pencil sharpener ~s
needed to achieve maximum throttling e~fect despite such wear.
AXter prolonged valve service, the erosion of the plug 54
and the tube liner 52 may become extensive enough to require
-- 11 --
~ 7~6 ~ ~
replacement of those parts. Such replacement is easily effected,
however, simply by unscrewing the nuts 72 and removing the valve
bonnet 26 from housing 12. This provides access to the hou~ing
chamber 13 so that the thro~tling tube 36 can be unscrewed from
the housing bottom wall 12a. Also, of course, the plug 54 can be
unscrewed easily from the coupling 9~. Af~er a fresh tube and
plug are ins~alled in place, the bonnet 26 can be re-secured ~o
the housing 12, all of this taking a very mïnimum amount of time.
Since the replacement parts are simple cylindrical pieces, they
can be formed relatively easily and inexpensively even though
made of hard abrasive-resistant material.
In some applications, to minimize the erosion of plug 54, a
coating of o~il can be main~ained over ~he plug end 54a. More
particularly, the plu~ 54 may be provided with an axial passage
; 15 extending to its end 54a as shown in do~ted lines at 118 in FI~.
1. Oil or other fluid under high pressure can then be supplied
to ~he passage 118 by way of a passage 122 in shaft 102
communica ion via a passage 124 in coupling 106 with a flexible
hose 126 leading out of enclosure 104. The high pressure oil
upon reaching the lower end of the passage 118 iSSU2S forth and
blankets the plug end 54a, protecting it from the abrasive action
-
of the incoming fluid.
Preferably ~he chamber 13 in the valve housing is
suf~iciently large in relation to tube 36 that the housing side
25 . wall 12b is spaced appreciably from ~he tube. That, coupled wi~h
the fact that the incoming fluid suffers a pressure drop upon
entering the chamber 13, means that the housing ~alls should not
- 12
~72~
be abraded to any great e~tent by the fluid. ~owever, to ev~n
further minimize the effec~s of the fluid on the housing walls, a
replaceable cylindrical baffle or liner indicated in dotted lines
at 148 in FIG. 1 can be positioned in the chamber to bear the
brunt of the fluid and direct it efficiently toward the valve
ou~le~ passage 16.
In some applications, in order to minimize localized erosion
of the plug end 54a and sleeve liner 52, provision may be made
for rotating the plug independently of its lineal ac~uation.
With such an arrangement, the opposing or mating edges or
segments of the plug and ~hrottling tube liner are shifted
circumferentially relative to one another. This is accomplished
in the illustrated valve by a gear drive 132 mounted in the wall
of enclosure 92. It includes a ring gear 134 engaged about-shaft
102 and whose center is broached to receive splines 136 formed on
that shaft. Gear 132 is mounted in the top wall of enclosure 92
between bushings 138. The gear meshes with a sprocket 142 driven
by an electric motor 146 mounted to the enclosure wall. Thus the
shaft 102 is ree to slide up and down relative to gear 134 in
response to actua~ions of the piston 108a. ~owever, the shaft
(and therefore plug 54) may also be rotated independently by
mo~or 146 when that is deemed necessary. Of course, in a non-
rotative valve emodiment, the gear dri~e 132 and splined rod 102
may be eliminated with the plug 5~ being coupled directly to a
longer piston rod 108.
It will be seen from the foregoing then that the present
valve is capable of controlling the flow of abrasive fluids such
- 13 -
' l1 7~
as coal slurry under high ~empera~ure and pressure conditionswithout sufferiny undue parts wear. Yet the valve is relatively
inexpensive to make. Such surface erosion as does occur is
confined primarily o two replaceable parts namely the throttling
plug 54 and throttling tube liner 520 ~owever, as those par~s
are eroded by the fluid, such erosion is compensated for by
advancing the plug further and further ~oward the throttling ~ube
liner thereby presenting fresh noneroded plug and lin~r surfac@s
to one another to a hieve maximum hro~ling~ When substantially
the entire length of the plug has been ~used up" in this fashion,
~he plug and eleeve (if need be) are easily replaceable with
fresh parts. Further, even those replacement parts are
rela~ively inexpensive since they are simple cylindrical shapes
which can be formed relatively easily using conventional
lS techniques. Resultantly~ my valve should find wide service
particularly in ~hose applications involving severe throttling
Gonditions.
It will aIso be seen ~hat the ob~ects set forth above, among
those made apparent from the preceding description, are
efficiently attained. Also, certain changes may be made in the
above construction without departlng from the scope of the
inventionO For example, the valve stem can be actuated manually
or by hydraulic, pneumatic or other motive devic~s. Also, fluid
can ke flowed through valve 10 in the opposite direction and
still the valve will have a long service li~e. Therefore, it is
intended that all matter contained in the above description or
shown in the accompanying drawing shall be interpreted as
illustr~tive and not in a limiti.ng serlse.
It is al30 to be under~tood that the following claims ar~.
intended to co~rer all of the generic and specific features of the
inventioFl herein descr ibed .
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