Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
1332034
B~CKGROUND OF THE INVENTION
The field of the present invention is pumps with heat
exchangers.
In pumps used in connection with hot liquids, such as
reactor cooling water, it is often advantageous or necessary to
cool the pump, or pump components such as mechanical seals. To
this end, heat exchangers may be provided with the pump to
provide a cooling function.
For example, U.S. Patent 3,478,689 discloses a high-
pressure, high temperature reactor circulating pump having a
thermal plate and a heat exchanger shield for cooling a shaft
seal. In addition, U~S. Patent No. 3,459,430 discloses a
mechanical seal assembly having cooling coils within a cooling
jacket. A recirculation impeller driven by the pump shaft causes
liquid to flow over the heat dissipating surfaces of a mechanical
seal cartridge and a radial bearing, to cool these components.
The heat absorbed in the liquid is dissipated from the cooling
coil into a liquid that flows over and around the coil.
An improved heat exchanger is described in U.S. Patent No.
4,005,747 for use with a pump assembly incorporating mechanical
seals, such that the seals are cooled not only during pump
operation, but also in the hot-stand-by condition. This heat
exchanger is constructed with a rotating baffle which defines the
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1332034 : ~
path of hot fluid flow and which when rotating, causes
rotational motion in the hot fluid. The heat exchanger is
designed so that the coolant flows in a defined path along
the pump shaft to the mechanical seals.
Although these known cooling techniques have
performed well in the past, a further improvement in the
cooling of the mechanical seals would prolong their useful
life and improve reliability.
This application is a division of commonly owned
Canadian Patent Application No. 560,898 filed March 9, 1988.
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SUMMARY OF THE INVENTION
The present invention is directed to improvements in
a pump having a pump cover and a hydrostatic bearing. In
particular, the invention provides a radially slotted keyway
spacer ring for providing alignment between the bearing and
the cover. The ring has a plurality of equally spaced apart
holes and at least four slots equally radially spaced apart
and radially oriented.
Xey means project from the cover, with each being
received in one of the grooves for aligning the cover and the
bearing. Bolts may pass through at least some of the holes
for connecting the aligned cover and bearing.
Other and further objects and advantages will appear
hereinafter.
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BRIEF DE~CRIPTION OF THE DR~WING8
In the drawings, wherein similar reference
characters denote similar elements throughout the several
views;
FIG. 1 is a perspective view of a pump and motor
assembly; --
FIG. 2 is a fragmentarily illustrated section view
: taken along line 2-2 of FIG. 1;
FIG. 3 is an enlarged fragmentarily illustrated
section view of the heat exchanger and pump elements
illustrated in FIG. 2;
: FIG. 4 is a section view taken along line 4-4 of :~
FIG. 3;
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: FIG. 5 is a section view taken along line 5-5 of
FIG. 3; :~
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E:IG. 6 is a section view taken along line 6-6 of FIG~ 3;
FIG. 7 is a section view taken along line 7-7 of FIG. 3;
FIG. 8 is a front elevational view of a seal injection
distribution ring;
FIG. 9 is a side elevational view in part section thereof; .
FIG.~ 10 is a front elevational view of the slotted keyway
spacer ring illustrated in FIG. 3;
FIG. 11 is a section view taken along line 11-11 of FIG. 10; .
and
FIG. 12 is a section view taken along line 12-12 of FIG. 3
; illustrating the engagement of the hydrostatic bearing, the slot
keyway spacer, and the pump cover.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT
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~:; Turning now in particular to the appended drawings, as shown
in FIG. 1, a pump assembly 20 includes a pump housing 22 having a
port 24, and a driver mount 26 attached to the pump housing 22. ~:.
.
With reference to FIGS. 2 and 3, a pump cover 34 is secured
to the pump housing 22 with cover clamp ring 32. The motor 26
: which is generally disposed at one end of the pump assembly 20 is ~.
attached to a shaft 42 extending substantially through the pump -.
assembly 20 and joined to an impeller 36 which is rotatable
within an impeller chamber 72 in the pump housing 22.
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With particular reference to FIG. 3, the impeller 36
includes a cylindrical journal 40 extending from the back surface
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of the impeller into a recess 73 in the impeller chamber 72. A
cylindrical hydrostatic bearing 3~ is joined to the cover 34 by a
ring of fasteners 46, such that the hydrostatic bearing 38
surrounds the ~ournal 40, thereby maintaining the journal and
impeller in position and providing a bearing function. To
simplify alignment of the hydrostatic bearing 38 during its
installation into the pump assembly 20, a slotted keyway spacer
ring 120 may be installed in between the pump cover 34 and the
hydrostatic bearing 33, as shown in FIG. 3.
In order to primarily contain the pumped or product fluid or
water within the impeller chamber 72, and to prevent the product
water from passing out of the pump housing 22 into the motor 26
along the shaft 42, a mechanical seal or seal cartridge assembly
50 is installed over the shaft 42 in between the motor 26 and the
impeller 36. In certain applications, the product water pressure
may reach 2500 psi so that the use of a multistage seal cartridge
assembly, such as the assembly disclosed in U.S. Patent
3,459,430, is appropriate. This type of seal relies on elastic ~;
materials and the very precise near engagement of solid sealing
rings with the shaft. As the product water being driven by the
impeller can reach 575 F, the seal 50 should be cooled in order
to maintain its sealing efectiveness. -
According to the present invention, a heat exchanger ;~
(collectively designated by 51) is provided within the pump
assembly 20 to cool the seal 50. Referring again to FIG. 3, the
heat exchanger 51 includes a rotating baffle sleeve 52 which is ;
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releasably but securely and intimately mounted onto the shaft 42.
The rotating baffle sleeve 52 includes a base 53 configured to
accurately match and mate with the profile of the shaft 42.
~ t the lower or impeller end of the base 53 is a lower
bridge 54 integral with and extending radially outwardly from the
base 53.- The lower bridge 54 is joined to a perpendicular lower
facing section 55 which extends towards a central position of the
heat exchanger and away from the impeller 36 in a direction
generally parallel to the base 53. The lower facing section 55
includes a tapered segment 56 at its end. Similarly, at the
upper or seal end of the base 53 is an upper bridge 57 integrally
joined with the base 53 and extending radially outwardly to join
an upper facing section 58 mounted perpendicularly thereto.
While the upper facing section 58 extends towards the lower
facing section 55 in a direction parallel to the base 53, a seal
baffle 59 ext~nds in the opposite direction and substantially
surrounds the entire seal 50.
To facilitate manufacture and assembly of the rotating
baffle sleeve 52, the sleeve may be formed by an upper baffle 61
and a lower baffle 63 releasably joined together at a joint 64.
A cooling cylinder 66 is generally suspended and fixed in
position within the space in the rotating baffle sleeve 52 formed
by the upper facing section 58, the lower facing section 55, and
the base 53. The cooling cylinder 66 is formed by an inner
enclosing cylinder 68 having a grooved outer surface, which is
spaced apart from an outer enclosing cylinder 67 which has a
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groovèd inner surface. The inner and outer enclosing ~cyli~iders
are joined together at their ends. The outer enclosing cylinder
67 extends beyond t}~e rotating baffle sleeve and is attached to
and supported by a barrel support 69. ~s the cooling cylinder
66 is suspended within the rotating baffle sleeve S2, a flow
passageway 74 is formed by the outside surfaces of the cooling
cylinder 66 and the inside surfaces of the rotating baffle sleeve
52. The flow passageway 74 opens at one end into the impeller
chamber 72, extends through the heat exchanger 51, over the seal
baffle 59 to a juncture 84 and then into a seal chamber 70.
As shown in FIGS. 4, 5, and 6, contained within the cooling
cylinder 66 is a spacer cylinder 65 having a plurality of
radially spaced apart grooves 60 on its outside surface. Similar
to the flow passageway 74, the grooves 60 on the spacer cylinder
65 form a component cooling water passageway 71 in between the
spacer cylinder 65 and the cooling cylinder 66. Passageway 71 is
linked to an inlet 78 and an outlet 79 formed within the barrel
support 69. A pair of ducts 75 in the barrel support 69 link the
inlet 78 and the outlet 79 to a component cooling water source
through a port 76 in the pump cover 34.
}~djacent to the component water passageway 76 is a seal
injection water supply duct 80 which supplies seal injection
water to an injection water distributor ring 90 positioned in
between the injection supply duct 80 and the duct junction 84
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adjacent to the seal 50. ;~
The seal injection distributor ring 90, as shown in FIGS. 8
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13320~4
and 9, comprises an annular ring having a plurality of
spaced apart distribution openings 92. The injection water
supply duct 80 connects to the distributor ring 90 at a
single location. As show in FIG. 3, the distributor
ring 90 is disposed within a recess in an upper flange 88
of the barrel support 69. As the injection water enters
the *istributor ring 90 it is uniformly distributed
circumferentially around the ring via the ring opening 92.
The openings 92 may vary in size, if so desired.
At the end of the barrel support 69 adjacent to the
impeller chamber recess 73 is a thermal shield 48 set
into an annular groove 45 in the barrel support 69. The
thermal shield 48 includes plural spaced apart rings 47 ~::
and 49 forming a stagnant water cavity 43 therebetween,
as best shown in FIG. 3. The insulation provided by the
thermal shield 48 acts to prevent sudden and extreme
temperature variations in the portion of the barrel
support facing the recess 73, thereby reducing temperature
related stresses in the barrel support 69. Alternatively,
the heat shield may comprise a thickened material section
at the end of the barrel support 69.
FIGS. 10, 11 and 12 illustrate a slotted keyway spacer
ring 120 which is disposed in between the pump cover 34
and the hydrostatic bearing 38. The slotted keyway
spacer rlng 120 has radially spaced apart holes 122 in
alignment with the fasteners 46 engagning the cover 34. In
addition, the spacer ring 120 includes four or more equally
spaced apart radial keyway slots 124 which engage keys
126 on the pump cover 34.
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i332034
The pump has two modes of operation, depending upon whether
seal injection water is available During normal operation, seal
injection water is available and flows through the duct 80, is
distributed by injection distributor ring 90 and runs into the
seal chamber 70. The seal injection water is preferably supplied
at approx. 105 F, so that the seal 50 and seal cartridge is
maintained at a relatively cool operating temperature. In
addition, the seal injection water is clean water so that dirt
and impurities are prevented from reaching the seal 50 and the
cartridge. The solid arrows in FIG. 3 represent the flow pattern
in the pump during normal operation with seal injection water,
and the phantom arrows represent the flow pattern when no seal
injection water is available.
Once the seal chamber 70 is filled with seal injection
water, a small portion of the water in the seal chamber 70 flows
through the seal 50 and the seal cartridge, and the remaining
seal injection water supply flows outwardly through the junction
84 through the heat exchange flow passageway 74 in the heat
exchanger 51, and then into the impeller chamber 72 where it
becomes part of the product water. Simultaneously, component
cooling water is provided through the ducts 76 and 75 and through
the inlet 78 into the cooling cylinder 66. The component cooling
water then circulates through the cooling cylinder 66, guided by
the openings and grooves in the spacer cylinder 65 and the inner
and outer enclosing cylinders 67 and 68, and then passes through
the outlet 79 and is returned to the component cooling water
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source. As the seal injection water flowing through the heat
exchange flow passageway 74 is at a relatively low temperature,
and at approxlmately the same temperature as the product cooling
water flowing within the product coollng water passageway 71,
there is little or no heat exchange occurring when seal injection
water is available.
However, in the second mode of operation of the pump, i.e.,
when there is no seal injection water available (or in pumps
which are not adapted to accept seal injection water) the
operation of the heat exchanger 51 becomes critical. When no
seal injection water is provided, the high temperature (e.g. 575
F) product water enters the flow passageway 74 from the impeller
chamber 72, flows through the heat exchanger 51 and the junction
84 and into the seal chamber 70. As the cooling cylinder 66 is
continuously provided with a flow of component cooling water at
e.g. 90 F, there is a very large temperature difference between
the product water flowing through passageway 74 and the component
cooling water flowing through passageway 71. Therefore, a high
rate of heat transfer occurs through the walls of the cooling
cylinder (i.e., through the outer enclosing cylinder 67 and the
inner enclosing cylinder 6~). Thus the product water is
substantially cooled as it flows through the heat exchanger 51
before it comes into contact with the seal SO and seal cartridge.
As a result, even in the absence of seal injection water, the
seal is maintained at an operational acceptable temperature.
Moreover, the rotating baffle sleeve helps in buffering
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temperature changes induced in the seal 50 and seal cartridge
and mitigates temperature related stresses in the shaft. ~;
The heat exchanger 51 achieves a high level of cooling
efficiency by virtue of the large amount of surface area
provided, the dual directional flow of the product cooling
water therein, as well as the counterflow cooling design.
While the seal baffle 59 provides an extended heat exchange
surface, it also insures that the seal chamber 70 is filled -
with injection water, before any injection water flows into ~
the heat exchanger 51 at startup. In addition, the centrifugal ~-
effect imparted to the water by the seal baffle tends to ~`
drive suspended particles outwardly and away from the seal 50.
Furthermore with the present construction a major heat transfer
area is located in a relatively cold region of the heat ~ -~
exchanger, i.e., the last pass of the product water through
the heat exchanger occurs adjacent to the relatively cool
upper baffle 61. This configuration helps to prevent a
reduction in cooling effectiveness caused by conductive heat
transfer from impeller chamber surfaces into the already ~`
cooled product water from toward the seal cartridge.
As the component cooling water flows continuously -~
regardless of the presence or absence of the seal injection ~-`
water, a very high temperature gradient is established
across the end of the barrel support 69, because component
cooling water at e.g. 90 F is separated from product water -~
at e.g. 575 F by a relatively thin wall. In order to `
reduce thermal stresses in this region, the thermal
shield 48 is provided at the end of the barrel
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1332034
support 69, and acts as an insulator therein.
The heat exchanger 51 is designed so that it may be
readily retrofitted onto existing pumps with replacement of
the existing pump cover. In addition, the heat exchanger 51
is easily removable from the pump assembly 20 for inspection
or service. Initially, the seal 50 is slidably removed from
the shaft 42. The upper baffle 61, which may be held in
position on the shaft with a lock ring, is then similarly
slidably removed from the shaft 42. With the upper baffle
61 now out of the way, the entire heat exchanger assembly 51
including the cooling cylinder 66 and its components 67, 68,
and 65, as well as the barrel support 69 carrying the ducts
75 and 76, the inlet 78 and outlet 79, and the thermal shield
49, can all then be removed as a single unit. Thereafter,
the lower baffle 63 may also be slidably removed from the
shaft 42. During reassembly, the above-described steps are
reversed.
During installation or replacement of the
hydrostatic bearing 38, the bearing is secured to the
radially slotted keyway spacer ring 120 via retainer bolts
;~ 128, as shown on FIG. 12. The keyway slots or grooves 124
in the spacer ring 120 are then engaged over the keys 126
protruding from the pump cover 34, in order to accurately
~position the bearing 38 over the journal 40 without the need
for repeated time consuming indicating measurements after the
initial installation of the hydrostatic bearing. The
radially slotted keyway spacer ring feature is a significant
advantage during bearing replacement because the pump may be
used
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1332034
ln nuclear power generation installations and become radioactive,
thereby severely limiting the amount of time any single operator
has available for servicing the pump.
Thus, a pump having an improved heat exchanger for cooling a
seal, as well as a novel seal injection water distributor ring, a
thermal shield, and a radially slotted keyway spacer ring for a
hydrostatic bearing are disclosed. While embodiments and
applications of this invention have been shown and described it
would be apparent to those skilled in he art that many more
modifications are possible without departing from the inventive
concepts herein. The invention, therefore, is not to be
restricted except in the spirit of the appended claims.
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