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Патент USA US3076422

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Feb. 5, 1963 ‘
:1 3,076,412
J. H. HARKER ETAL
METHOD AND APPARATUS FOR MAINTAINING ROTATING PUMP SEALS
2‘ Sheets-Sheet 1
Filed March 4, 1959
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Feb. 5, 1963
3,076,412
J. H. HARKER ETAL
METHOD AND APPARATUS FOR MAINTAINING ROTATING PUMP SEALS
Filed March 4, 1959
2 Sheets-Sheet 2
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3,076,412
ROTATING PUMP SEALS
John H. Harker, Park Ridge, Ralph W. Janetz, Park
Ridge Manor, and Jack Keyes, Park Ridge, 11]., as
Applications involving the pumping of high-temperature
3,075,412
this is best accomplished by applying reaction forces to
liquid tending to swirl in the seal well and thereby prevent,
the establishment of a swirling ring of liquid. In the pre
ferred practice of the invention, baffles are interposed in
the seal well to disrupt the swirl path of the seal well
METHOD AND APPARATUS FOR MAINTAiNllsYG
srgrrors to Bell & Gossett Company, a corporation of
Illinois
Filed Mar. 4, 1959, Ser. No. 797,190
3 Claims. (Cl. 103-411)
>3
pgtenred Feb. 5., 1963'
liquid and the battles are preferably in the form of ribs
rigidly secured to the wall structure that borders and
de?nes the seal well.
Other objects and advantages will become apparent
10 during the course of the following description.
liquids, which are now quite numerous, necessarily re
quire that the pump parts, and this includes the rotating
seal, also operate at high temperatures. Thus the seal
In the accompanying drawings forming a part of this
speci?cation and in which like numerals are employed
to designate like parts throughout the same:
FIG. 1 is a side-elevational view of a centrifugal pump
structure is faced with rigorous conditions at the very 15 incorporating the teachings of the present invention, with
outset.
'
parts broken away and sectioned to facilitate the dis
. One pump application particularly subject to failure of
closure;
'
FIG. 2 is an enlarged sectional view of the seal well
the rotating pump seals is found in closed hot water
region of the pump of FIG. 1;
systems for boilers. In these boiler systems the circulat
’ PEG. 3 is an end view of the pump seal plate of the
ing pump is called upon to handle water at temperatures
preferred constructional embodiment;
_
in the range of 185° F. to 250° F. and in many instances
the water temperature is as high as 400° F.
In recent years, rotating seal assemblies of a type that
FIG. 4 is an end view of an alternative seal plate con
struction in accordance with the invention; and
FIG. 5 is a simpli?ed diagrammatic illustration of a
has long been successfully employed in the seal wells of
centrifugal pump constructions have suffered a severely 25 closed hot water heating system to which the invention
?nds particular application.
high rate of failure when used in pumping systems han
For purposes of disclosure the invention is illustrated
dling high-temperature liquids.
in its application to a conventional centrifugal pump, des
In general the blame for this high rate of seal failures
ignated generally as 10.
'
has been directed at the seal structure itself and while
various alternative seal structures have been considered, 30 The illustrated pump is of the type having a volute
casing 11 formed with a liquid inlet and suction passage
the high failure rate remained and even increased as more
12 and a pressure chamber 13. Numeral 14 designates
applications involving pumping of higher temperature
part of a bracket adapted for connection with a motor.
liquids came into being. Numerous instances are known
support (not shown). A rotatable drive shaft 15 extends
where seal structures have failed after but a single day’s
service.
35 through a seal plate 16 that constitutes one end wall of‘
the casing 11 and is keyed to an impeller 17 that is ro
The principal object of the present invention is to pro
tatable in the volute casing to draw liquid through the in~
vide a method and apparatus for eliminating the high rate
let and suction passage 12. and discharge it into the pres
of failure of seal structures employed in pumps used
in systems for handling high-temperature liquids.
A further object of the invention is to eliminate destruc 40
sure chamber 13.
7
Referring now more particularly to FIG. 2, the seal
tive overheating of the seal structures by continuously
plate 15 includes wall structure 16W surrounding and
maintaining a supply of liquid in direct contact with the
de?ning a seal well 18, and a conventional seal assembly
is shown at iii in encircling relation to the shaft. The
seal assembly may include a carbon ring 20 slidable rela
tive to the shaft and mounted for rotation therewith. In‘
seal structures to ensure proper lubrication and cooling
of the seal faces thereof.
Still a further object of the invention is to provide an
improved closed hot water system wherein the circulating
pump of the present invention is combined with means in
the system for trapping air separating from the water in
the system.
According to the teachings of the present invention, the
failure of the pump seal structures employed in applica
tions involving pumping of high-temperature liquids arises
from the ability of high-temperature liquids to more
readily release gas and the fact that the shaft rotating in
the seal well tends to set up a centrifuging action and
drive the liquid in the seal well in an outwardly swirling
path in the general direction of shaft rotation. This cen
trifuging action encourages the release of gas from the
liquid; and the liquid, being heavier, tends to occupy the
outer region of the seal well and leave a gas pocket sur
rounding and thermally isolating the seal structure. When
this condition exists, the heat generated at the seal is not
- the illustrated construction the seal plate receives a sta
tionary seal ring 21 of Remite or other suitable seal face
material that is mounted to present a seal face for engage.
ment with the seal face of the rotatable carbon ring 20.
During normal operation of a pump of this type, the,
seal well is ?lled by liquid returning from the pressure
chamber along leakage paths such as are indicated by
the arrows designated 22. The action of the rotating
shaft continuously moves liquid around in the seal Well‘
so that circulation of the seal well liquid continues at a
rate normally sufficient to ensure proper cooling of the.
seal structure. It will be understood that the interengag
ing seal faces of the rings 20 and 21 continuously gener
ate heat by friction, and it is important that liquid occupy ;
the seal well for contacting the seal rings and lubricating
and cooling these seal faces.
'
Heating of the seals is also accelerated in the absence of
As explained previously, in recent years the failure
rate of seal structures used in centrifugal pumps handling"
high-temperature liquids has been enormous, partly be
liquid wetting and lubricating the seal faces.
cause the seal naturally runs at a higher temperature
. carried away and the seal quickly overheats and fails.
when it is in the presence of high-temperature liquids.
liquids that are not heavily gas laden, since the heat
According to the present invention, however, it has been
observed by means of elaborate experimental procedures
generated locally at the seal tends to vaporize some of the
that the liquid in the seal well is set into a swirling
liquid and the vapor is trapped around the seal in the
form of a gas pocket.
70 motion by the action of the shaft rotating in the seal"
well and this swirling motion encourages the'liquid to,
Thus the solution to the present problem of seal failure
‘release gas, which is then trapped in a pocket that sur
is to maintain liquid in'contact with the seal structure, and
The central gas pocket condition can arise even with
.
.
y
.
3,076,412
-
rounds the seal structure. Thus the seal well liquid is
effectively excluded from contact with the seal and it
cannot properly cool and lubricate the seal. Failure re
4
be of the type illustrated in FIG. 2 of Tidd’s US. Patent
No. 2,500,621, the disclosure of which, to the extent it
is not inconsistent herewith, is speci?cally incorporated
sults quickly when this gas pocket condition develops in
the seal well.
by reference. A branch line 31 extends from the boiler
lem.
In the preferred construction, best shown in FIGS. 2
will permit.
?tting 30, which is the point of no pressure change of
Since the seal failure rate in centrifugal pumps handling
the system, to a sutiable expansion tank 32 and includes
high-temperature liquid is common to all presently
a tank ?tting 33 which may be of the type shown in
known commercial pumps, the seal structure itself has
FIG. 2 of Tidd’s US. Patent No. 2,395,697, the disclo
‘been condemned by many in the ?eld, but it will now be
sure of which, to the extent it is not inconsistent here
apparent that the problem does not reside in the seal 10 with, is speci?cally incorporated by reference.
construction, but, rather, in the pump arrangements
As is explained in these U.S. patents, the boiler ?tting
which entertain the development of the gas pocket in
and tank ?tting arrangements facilitate separation and
the seal well.
trapping of air in the expansion tank and it has been
Therefore, according to the present invention, the seal
found that when the pump construction 10, such as is
structure is cooled by continuously developing reaction 15 shown in FIGS. 1-4, is employed as the circulating pump
forces against liquid tending to swirl outwardly in the seal
of a closed hot water system that is provided with suitable
well in the direction of shaft rotation to continuously di
air separation and trapping equipment for the general
vert or de?ect such liquid back to the seal structure. Pref
purposes described in the aforementioned Tidd' patents,
erably, the reaction forces should be such that the basic
seal failure problems arising from,v gas pocket formations
centrifuging action never matures into the development of 20 in the seal well are eliminated. It will be appreciated, of
an actual gas pocket.
course, that the invention allows substantial improvement
In the preferred practice of the present invention, the
in the seal performance in, closed hot water heating sys
gas pocket is substantially eliminated‘ by providing sta
tems that do not provide for effective separation and
tionary de?ector structure in the form of ribs on the seal
trapping of air, but important additional performance im
plate wall structure that surrounds the seal well, with
provements are attributable to the combination of the
the ribs projecting into the seal well to intercept the
present pump with the particular type of closed hot water
path of liquid tending to swirl around‘ the shaft in the
heating system.
direction of rotation. The number, arrangement, and
‘It should be understood that the invention ?nds general
con?guration of the ribs may be variously altered and in
application to centrifugal pumps irrespective of the details
many instances will depend mainly upon the running
of the seal structure itself and irrespective of detailed
clearances existing in the seal well between the seal plate
variations in the construction of the impeller and the pres
and. the impeller. Any rib arrangement capable of pre
sure chamber of the pump.
venting the swirling or centrifuging action of the liquid
it should be understood that the description of the
in the seal well to an extent sufficient to substantially con
preferred form of the invention is for the purpose of
tinuously maintain liquid in contact with the seal structure
complying with section 112, title 35, of the US. Code and
will satisfactorily eliminate the present seal failure prob
that the claims should be construed as broadly as prior art
and 3, the ribs are shown at 24 and are ararnged in a
common radial plane on opposite sides of the shaft to
substantially ?ll a clearance space between the shaft and
the outer seal well wall. Only two ribs are shown, as
We claim:
1. In a centrifugal pump of the type that includes a
casing having a liquid inlet leading to a suction passage
and a pressure chamber leading to a liquid outlet, said
casing having wall structure bordering and de?ning a
seal well with said wall structure having a single opening,
a rotatable shaft projecting through said opening and
in the general form of inwardly spiralling blades projec 45 seal well and carrying an impeller for rotation in said
tions across the seal well from the end wall thereof and
casing, and a seal assembly in said seal well and includ
spiralling inwardly in the direction of shaft rotation. to
ing relatively rotatable seal rings encircling said shaft to
divert and redirect liquid tending to swirl about the shaft
provide a seal across said shaft opening of said wall struc
along paths leading back to the seal structure, as indi
ture to substantially eliminate all- ?uid ?ow from said
cated by the arrows designated 25. The arrangement 50 seal well through said well structure, said‘ pump having
of these blade-like ribs also acts to baffle the seal well
a running clearance leakage path existing between said
for substantially preventing undesirable swirling of the
impeller and said seal well Wall structure, said shaft being
liquid such as would cause separation of the liquid and
rotatable in said casing to rotate said impeller and draw
gas. It should be understood that while it is preferred
liquid through said suction passage for discharge into said
that the ribs extend a sufficient distance axially of the 55 pressure chamber with said shaft rotation producing forces
seal well to provide a substantially complete baffle,
tending to swirl liquid in said seal well so as to create a
it is contemplated that they be located only at the region
solid liquid annulus that maintains a central gas pocket
of the seal rings such that they would not totally preclude
around said seal rings, means for preventing a gas pocket
the development of an air pocket but that would neverthe
around said seal rings and including ribs stationarily ?xed
less continuously supply suf?cient liquid to the seal faces 60 to said wall structure and projecting through said seal well
to. effectively cool and lubricate them.
for de?ecting contact with liquid therein tending to swirl
While. many straight-through type high-temperature
about said shaft for redirecting such liquid inwardly to the
they have proven sufficient, but more can be provided.
In an alternative construction, the ribs 24' are shaped
pumping applications have been seriously hampered by
seal problems of the type referred to, one particularly
severe problem resides in the closed hot water heating
system applications wherein water is handled at tempera
seal rings, said ribs extending from close proximity to
points where said leakage path enters said seal cavity and
leading towards the seal rings to prevent the establishment
of a solid liquid annulus at any point in said seal well
intermediate of said entrance points and said seal rings.
2. In a centrifugal pump of the type that includes a
or 26 connected through a supply line 27 to one or more
radiators 28. The circulating pump 10 of the type de 70 casing having a liquid inlet leading to a suction passage
and a pressure chamber leading to a liquid outlet, said
scribed herein is connected in the supply line 27 so that
casing having wall structure bordering and de?ning a
the suction side of the pump is as close as possible to
seal well with said wall structure having a single opening,
the point of no pressure change of the system. The
a rotatable shaft projecting through said opening and seal
water is returned to the boiler over a return line 29.
well and carrying an impeller for rotation in said casing,
The supply line includes a boiler ?tting 30 which may 75 and a seal assembly in said seal well and including rela
tures as high as 400° F. One such system is indicated
diagramamtically in FIG. 5 as including a hot water boil
3,076,412
5
tively rotatable seal rings encircling said shaft to provide
a seal across said shaft opening of said wall structure to
substantially eliminate all ?uid flow from said seal well
through said wall structure, said pump having a running
6
and said seal well wall structure, said shaft being ro
tatable in said casing to rotate said impeller for drawing
liquid through said suction passage and for discharging
such liquid into said pressure chamber with said shaft
clearance leakage path existing between said impeller and
rotation producing forces tending to swirl liquid in said
said seal well wall structure, said shaft being rotatable in
seal well so as to create a solid liquid annulus that main
tains a central gas pocket around said seal rings, sta
tionary rib structure ?xed to said wall structure and posi
tioned in said seal well for deflecting contact with liquid
swirl liquid in said seal well so as to create a solid liquid 10 therein tending to swirl about said shaft for redirecting
such liquid inwardly to the seal rings, said rib structure ex
annulus that maintains a central gas pocket around said
tending from close proximity to points where said leakage
seal rings, rigid rib structure on said seal well wall and
said casing to rotate said impeller and draw liquid through
said suction passage for discharge into said pressure cham
ber with said shaft rotation producing forces tending to
projecting into the path of liquid swirling about said shaft
path enters said seal cavity and leading towards the seal
to divert such liquid in different directions, said rib struc
rings to prevent the establishment of a solid liquid an—
ture providing paths for diverting swirling liquid inwardly 15 nulus at any point in said seal well intermediate of said
entrance points and said seal rings.
to said seal rings for eliminating a gas pocket there
around.
References Cited in the ?le of this patent
3. In a centrifugal pump of the type that includes a
UNITED STATES PATENTS
casing having a liquid inlet leading to a suction passage
and a pressure chamber leading to a liquid outlet, said 20
768,911
Schoene ______________ __ Aug. 30, 1904
casing having wall structure bordering and de?ning a seal
1,755,430
Crosthwait ___________ __ Apr. 22, 1930
Well with said wall structure having a single opening, a
1,832,398
Jennings ______________ .__ Nov. 17, 1931
rotatable shaft projecting through said opening and seal
well and carrying an impeller for rotation in said casing,
and a seal assembly in said seal well and including rela 25
tively rotatable seal rings encircling said shaft to pro
vide a seal across said shaft opening of said wall struc
ture to substantially eliminate all fluid flow from said seal
well through said wall structure, said pump having a run
ning clearance leakage path existing between said impeller 30
2,395,697
Tidd _________________ __ Feb. 26, 1946
2,402,995
Garraway _____________ __ July 2, 1946
2,500,621
2,777,395
2,843,404
Tidd ________________ .__ Mar. 14, 1950
Disbrow ______________ __ Jan. 15, 1957
Janetz ________________ __ July 15, 1958
276,593
Germany _____________ __ July 15, 1914
FOREIGN PATENTS
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