U.S. patent number 3,670,810 [Application Number 05/106,863] was granted by the patent office on 1972-06-20 for heat exchanger.
This patent grant is currently assigned to Atomic Power Development Associates, Inc.. Invention is credited to Robert C. Allen, Sr..
United States Patent |
3,670,810 |
Allen, Sr. |
June 20, 1972 |
HEAT EXCHANGER
Abstract
A heat exchanger characterized by a vessel containing a
plurality of tubes passing therethrough and an upper cover assembly
having a first ring-shaped tube sheet and a header assembly mounted
on said cover assembly and having a second ring-shaped tube sheet
disposed above said first tube sheet in spaced relationship to a
drain space between the two tube sheets, and means for connecting
the header to the vessel to provide expansion movement of the
header assembly with respect to the vessel.
Inventors: |
Allen, Sr.; Robert C.
(Wauwatosa, WI) |
Assignee: |
Atomic Power Development
Associates, Inc. (Detroit, MI)
|
Family
ID: |
22313662 |
Appl.
No.: |
05/106,863 |
Filed: |
January 15, 1971 |
Current U.S.
Class: |
165/70;
165/134.1; 165/81; 165/158 |
Current CPC
Class: |
F22B
1/063 (20130101); F28F 9/0239 (20130101) |
Current International
Class: |
F22B
1/00 (20060101); F22B 1/06 (20060101); F28F
9/02 (20060101); F28f 011/00 () |
Field of
Search: |
;165/70 |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Dority, Jr.; Carroll B.
Claims
What is claimed and desired to be secured by Letters Patent is:
1. A heat exchanger comprising a vessel having an internal heat
exchange chamber, a plurality of tubes passing through said
chamber, header means mounted towards the upper end of said vessel,
an upper ring-shaped tube sheet forming a bottom portion of said
header means, a spaced lower ring-shaped tube sheet forming a drain
space between said tube sheets, said tubes passing through said
sheets and the ends thereof opening onto said header means, said
tubes being connected to said lower tube sheet by rolling and said
tubes being connected to said upper tube sheets by rolling and
welding, said lower tube sheet being fixedly connected to said
vessel, means for connecting said upper tube sheet to said lower
tube sheet to prevent vertical movement and to allow lateral
movement therebetween.
2. A heat exchanger comprising a vessel having an internal heat
exchange chamber, a plurality of heat exchange tubes passing
through said heat exchanger chamber, an upper cover assembly for
said vessel, a ring-shaped header assembly, means mounting said
header assembly on said cover assembly to prevent vertical movement
and to allow lateral movement therebetween, an outlet for said
header assembly, said cover assembly carrying a first ring-shaped
tube sheet through which said tubes pass, means for substantially
limiting the leakage between said tubes and said tube sheet, said
steam header assembly carrying as an integral part thereof a second
ring-shaped tube sheet for receiving the upper ends of said tubes
in fluid flow relation, means for substantially limiting the
leakage between said tubes and said second tube sheet, said second
tube sheet being spaced from said first tube sheet to provide a
drain space therebetween, drain means for removing leakage from
said drain space, and seal rings being interposed between the steam
header and the cover assembly for preventing leakage from said
drain space.
3. A heat exchanger according to claim 2 wherein said vessel has
upper water inlets and lower steam outlets and wherein said heat
exchanger further comprises a ring-shaped water header assembly
mounted on said cover assembly for receiving water from a water
inlet, said tubes being connected to said water header assembly in
fluid flow communication.
4. A heat exchanger according to claim 2, wherein said tubes are
connected to said first tube sheet by rolling, and wherein said
tubes are connected to said second tube sheet by rolling and
welding, and wherein said drain means for removing leakage from
said drain space comprises a plurality of spaced drain openings
disposed around the periphery of the cover assembly.
5. A heat exchanger according to claim 2 wherein said means
mounting said header assembly on said cover assembly to prevent
vertical movement and to allow lateral movement therebetween
comprises bolts extending between said steam header assembly and
said cover assembly, the bolt holes in said steam header assembly
being of substantially larger diameter than the diameter of the
bolts.
6. A heat exchanger comprising a vessel having an internal heat
exchange chamber, a plurality of heat exchange tubes passing
through said heat exchange chamber, said vessel having upper sodium
inlets and a lower sodium outlet, an upper cover assembly for said
vessel, a ring-shaped water header assembly mounted on said cover
assembly for receiving water from a water inlet, said tubes being
connected to said header assembly in fluid flow communication, a
ring-shaped steam header assembly, means mounting said steam header
assembly on said cover assembly, an outlet for said steam header
assembly, said cover assembly carrying a first ring-shaped tube
sheet through which said tubes pass, said tubes being connected to
said first tube sheet by rolling, said means mounting said steam
header assembly on said cover assembly comprising bolts mounted in
enlarged bolt holes in said steam header assembly to permit radial
movement of said steam header assembly with respect to said cover
assembly, said steam header assembly carrying as an integral part
thereof a second ring-shaped tube sheet for receiving the upper
ends of said tubes in fluid flow relation, said tubes being
connected to said second tube sheet by rolling and welding, a top
closure plate for said steam header, said top closure plate being
removable for providing access to the upper ends of said tubes,
said second tube sheet being spaced from said first tube sheet to
provide a drain space therebetween, a plurality of spaced drain
openings being provided around the periphery of the cover assembly
for removing leakage from said drain space, and seal rings being
interposed between the steam header and the cover assembly for
preventing leakage from said drain space.
7. A heat exchanger comprising a vessel having an internal heat
exchange chamber, a plurality of tubes passing through said
chamber, a cover assembly for closing said chamber, said cover
assembly having as an integral portion thereof a first ring-shaped
tube sheet through which said tubes pass, means for substantially
limiting the leakage between said tubes and said tube sheet, a
ring-shaped header assembly having as an integral part thereof a
second ring-shaped tube sheet for receiving the upper ends of said
tubes in fluid flow relation, means for substantially limiting the
leakage between said tubes and said second tube sheet, said second
tube sheet being spaced from said first tube sheet thereby
providing a drain space, drain means for removing leakage from said
drain space, said header assembly being substantially free floating
except for support furnished by said tubes, means for aligning said
header assembly with respect to said cover assembly, sealing means
interposed between the header assembly and said cover assembly.
8. A heat exchanger according to claim 7 wherein said tubes are
connected to said first tube sheet by rolling and wherein said
tubes are connected to said second tube sheet by rolling and
welding and wherein means are included for providing access to said
drain space.
9. A heat exchanger according to claim 7 further comprising spring
support means interposed between said cover assembly and said
header assembly for providing support for said header assembly.
10. A heat exchanger according to claim 7 wherein said means for
aligning said header assembly with respect to said cover assembly
comprises four spaced vertically disposed elongated keyways in said
cover assembly and said header assembly having mating keyways for
receiving said keys.
11. A heat exchanger according to claim 7 wherein said sealing
means comprises a first pair of sealing rings including a lower
ring and an upper ring which are mounted for engagement with the
header assembly, and a second pair of sealing rings including a
lower ring and an upper ring which are mounted for engagement with
the cover assembly, said sealing rings being in the form of
segments and being provided with alignment pins for keeping said
rings in horizontal alignment, said rings being provided with
tapped holes for removal, a first segment retainer retaining the
sealing rings in vertical position and a second segment retainer
for retaining the first retainer in position whereby said sealing
means may be removed without disturbing said tubes and whereby said
sealing means permit free radial and vertical movement of said
header assembly.
12. A heat exchanger comprising a vessel having an internal heat
exchange chamber, a plurality of tubes passing through said
chamber, a cover assembly for closing said chamber, said cover
assembly having as an integral portion thereof a first ring-shaped
tube sheet through which said tubes pass, said tubes being
connected to said first tube sheet by rolling, said cover assembly
further comprising an annular support member, a ring-shaped header
assembly having as an integral part thereof a second ring-shaped
tube sheet for receiving the upper ends of said tubes in fluid flow
relation, said tubes being connected to said second tube sheet by
rolling and welding, said second tube sheet being spaced from said
first tube sheet thereby providing a drain space, half-rings being
removably mounted on said cover for providing access to said drain
space, said cover providing a plurality of spaced drain openings
for said drain space, spring support means interposed between said
cover and said annular support member, said steam header assembly
being substantially free floating except for support furnished by
said tubes and said external spring supports, said annular support
member having four equally spaced vertically disposed elongated
keys, said header assembly having mating keyways for said keys,
sealing means interposed between the steam header assembly and said
cover assembly, said sealing means comprising a first pair of
sealing rings including a lower ring and an upper ring which are
mounted for engagement with the header assembly, and a second pair
of sealing rings including a lower ring and an upper ring which are
mounted for engagement with the cover assembly, said sealing rings
being in the form of segments and being provided with alignment
pins for keeping said rings in horizontal alignment, said rings
being provided with tapped holes for removal, a first segmented
retainer retaining the sealing rings in vertical position and a
second segmented retainer for retaining the first retainer in
position whereby said sealing means may be removed without
disturbing said tubes and whereby said sealing means permits free
radial and vertical movement of said steam header assembly.
Description
This invention relates to heat exchangers and it is particularly
adapted, among other possible uses, for preventing water or steam
leakage into sodium in steam generators heated with liquid sodium,
for example. Steam generators of this nature are particularly
suited for use in conjunction with nuclear reactors.
Heretofore, double tubes with double tube sheets were employed in
steam generators or heat exchangers to prevent mixture of the main
flows of the cycling fluids when leakage occurred. These introduced
heat transfer resistance and were expensive and difficult to
fabricate. My contribution to the art is a new heat exchanger which
is an improvement over such prior art devices, and it involves a
novel combination of features combined in such a way as to afford a
very effective solution to the difficulties encountered with the
prior art, as will become apparent as the description proceeds.
Related patents in this art include:
15,553 S.M. Lilliie April 18, 1919 1,439,283 C.P. Astrom December
19, 1922 1,962,170 L.I. Blennerhasset June 12, 1934 1,987,891 F.W.
Cattanach January 15, 1935 2,660,411 N. Weber November 24, 1953
2,893,701 A. Bell July 7, 1959
Briefly, my invention contemplates the provision of a new and
improved heat exchanger characterized by a vessel having an
internal heat exchange chamber with a plurality of heat exchange
tubes passing therethrough. The vessel is provided with a cover
which contains a first tube sheet. An upper header means is mounted
on said cover and contains a second tube sheet which is disposed in
spaced relationship with respect to the first tube sheet, thereby
providing a space between the tube sheets for draining off fluid
leaking from the header as well as fluid leaking from the main
portion of the vessel. Means are provided for connecting the header
to the vessel cover, which allows for differential expansion
therebetween.
There has thus been outlined rather broadly the more important
features of the invention in order that the detailed description
thereof that follows may be better understood, and in order that
the present contribution to the art may be better appreciated.
There are, of course, additional features of the invention that
will be described more fully hereinafter. Those skilled in the art
will appreciate that the conception on which this disclosure is
based may readily be utilized as the basis for the designing of
other structures for carrying out the several purposes of the
invention. It is important, therefore, that this disclosure be
regarded as including such equivalent constructions as do not
depart from the spirit and scope of the invention.
Several embodiments of the invention have been chosen for purposes
of illustration and description, and are shown in the accompanying
drawings, forming a part of the specification, wherein:
FIG. 1 is a medial, longitudinal, sectional view of a vertically
disposed steam generator constructed in accordance with the concept
of this invention;
FIG. 2 is an enlarged, fragmentary view of a portion of the steam
generator of FIG. 1, showing details of the header means, double
tube sheets and heat exchanger tubes;
FIG. 3 is an enlarged, sectional view taken along the line
indicated at 3--3 in FIG. 1;
FIG. 4 is an enlarged, fragmentary view of a portion of a steam
generator similar to FIG. 2, but showing a modified form of
connection between the header means and the tube sheets;
FIG. 5 is an enlarged, sectional view similar to FIG. 3, but
showing the form of connection between the header means and the
tube sheets of FIG. 4;
FIGS. 6 and 7 are enlarged, fragmentary, longitudinal, sectional
views showing details of seal rings interposed between the upper
and lower tube sheets;
FIG. 8 is an enlarged, fragmentary, longitudinal, sectional view of
the seal rings and alignment pins; and
FIG. 9 is an enlarged, exploded, perspective view showing the
sealing ring assembly.
In FIG. 1 there is shown a sodium heated steam generator comprising
a vessel 10 having an internal heat exchange chamber 12, and a
plurality of heat exchanger tubes 14 passing through said heat
exchange chamber 12. The vessel is provided with upper sodium
inlets 16 and a lower sodium outlet 18. Normally, in a steam
generator of this type, sodium which has been heated in a nuclear
reactor (not shown) is received through the sodium inlet and passes
downwardly through the vessel 10 wherein it gives up heat to a
medium such as steam and then passes out through the outlet 18 and
back to the nuclear reactor, thereby forming a closed cycle. The
operating level of the liquid sodium in the vessel is between an
upper level 20 and a lower level 22. The space 23 above the liquid
sodium is filled with argon under a slight positive pressure.
Shroud baffles 24 are mounted adjacent the sodium inlets and an
internal shroud 26 is provided. The tubes 14 are retained by means
of restraint clips 28. The vessel 10 is closed by means of a steam
cover 30 and, for protection purposes, a relief diaphragm 31 is
mounted on the top thereof.
Still referring to FIG. 1, a water inlet 32 is provided, which
receives water from a condenser, (not shown) in a conventional
steam plant, for example. Water passes through the inlet and into a
ring-shaped water header assembly 34, from where it passes into the
tubes 14. Tubes 14 pass through the heat exchanger 12 wherein the
water is converted into steam before returning to a ring-shaped
steam header assembly 36, and an outlet 38. Normally the steam is
led to a steam turbine (not shown) when the heat exchanger is
employed in conjunction with a conventional steam power plant.
As best seen in FIG. 2, I provide, according to my invention, a
construction which permits differential expansion between the steam
header assembly 36 and the cover 30, FIGS. 2 and 3. This cover is
fixedly attached to the vessel 10, as by means of bolts 40, and it
carries as an integral portion thereof a first ring-shaped tube
sheet 42, FIG. 2, through which the tubes 14 pass. Sufficient gas
tightness between the tubes and the first tube sheets by
conventional rolling procedures is carried out from the outside of
the cover. The steam header assembly 36 is a separate ring-shaped
casting which is mounted on a surface 44 of the cover 30 by means
of bolts 46. Bolt holes 48 in the header assembly 36 are fabricated
substantially larger than the bolts 46 to permit radial movement of
the header assembly 36 with respect to the cover 30. That is, the
bolts 46 restrain the header from vertical movement with respect to
the cover, but they permit radial sliding movement at the support
surface, due to the differential expansion caused by the
temperature difference between the outlet steam and the adjacent
structure.
The steam header assembly 36, FIG. 2, is closed by means of a top
closure plate 50 bolted thereon, as by means of bolts 52. This
plate is removable to provide access to the upper ends of the tubes
14. The steam header assembly carries as an integral part thereof a
second ring-shaped tube sheet 54 for receiving the upper ends of
the tubes 14 in fluid flow relation. The tubes are connected to the
tube sheet 54 by rolling and welding, as at 56. The second tube
sheet 54 is spaced from the first tube sheet 42 to provide a drain
space 58 therebetween. The vertical height of the drain space is
selected based on the bending stresses in the tubes. A plurality of
spaced drain openings 60 are provided around the periphery of the
cover for removing leakage containing small amounts of water, water
vapor, argon gas, hydrogen gas and sodium hydroxide. The total
amounts of this leakage can easily be taken care of by established
disposal means available in all nuclear plants. In a typical
installation, the pressure in the steam header 36 is of the order
of about 2,400 p.s.i. and the pressure in the leak-off space 58 is
approximately equal to that of the atmosphere. The argon cover gas
23 has a pressure which is higher than atmosphere pressure by about
a few inches water gauge. Accordingly, leakage from both directions
is toward the drain space 58. The leakage with rolled tubes is very
small, so that the sodium vapor which reaches the drain space
through the argon gas is practically negligible. The construction
provides for a tube failure. The greater probability is that a tube
failure would permit the flow of water or steam into the drain
space 58. A sufficient number of drains are provided for
accommodating this flow in order to prevent the steam pressure in
this space from exceeding the argon pressure below the first tube
sheet 42 in the event of a complete failure of one tube.
Seal rings 62, FIG. 2, are interposed between the steam header 36
and the cover 30 for preventing leakage from the drain space 58.
This seal allows radial expansion movement between the two
members.
It will be particularly appreciated that the water header assembly
34, FIG. 1, is constructed in a manner substantially the same as
the steam header assembly 36 to permit differential expansion
between the water header assembly and the cover 30 and to provide a
drain 64 between a first tube sheet 66 and a second tube sheet
68.
When the temperature difference between the water inlet and steam
outlet and their respective adjacent structures is sufficiently
great to result in objectionable stresses in the space between the
first and second tube sheets, the embodiment of FIGS. 4-9 is
employed. In this embodiment there is a ring-shaped steam header
assembly 70 which is mounted on a cover assembly 72. The steam
header assembly 70 has a steam outlet 73. The cover is fixedly
attached to the vessel 10, as by means of bolts 74, and it carries
as an integral portion thereof, a first ring-shaped tube sheet 76,
FIG. 4, through which the tubes 14 pass. Conventional rolling
procedures carried out from the outside of the cover provide
substantial gas tightness between the tubes and the first tube
sheet 76. Removable half-rings 78 are mounted on the cover 72 as at
80, and the cover assembly further comprises an annular support
member 82 which is mounted together with the half-rings on the
surface 80 by means of bolts 83. The half rings are removable for
purposes of providing access to a drain space 84.
The ring-shaped steam header assembly 70, FIG. 4, carries as an
integral part thereof a second ring-shaped tube sheet 86 for
receiving the upper ends of the tubes 14 in fluid flow
relationship. The tubes are connected to the tube sheet 86 by
rolling and welding at 88. The second tube sheet 86 is spaced from
the first tube sheet 76, thereby providing a drain space 84. This
drain space serves for removing an accumulation of sodium oxide
that could form if excessive leakage occurred at the tube junctions
at the steam ends concurrently with argon containing sodium vapor
leaking from the first tube sheet. A plurality of spaced drain
openings 90 are provided around the periphery of the cover 72 for
removing the leakage. The drain openings are connected to
conventional disposal means available in all nuclear plants. The
construction provides for tube failure in a manner similar to that
described hereinbefore in connection with the embodiment of FIGS. 2
and 3.
The ring-shaped steam header assembly 70, FIG. 4, is substantially
free-floating. That is, it is not supported vertically except by
the tubes 14 and external spring supports 92. Weighted levers could
be used instead of the spring supports, if desired. As seen in
FIGS. 4 and 5, the annular support member 82 has four equally
spaced vertically disposed elongated keys 94, which fit into
keyways 96 in the header assembly 70, thereby to provide adequate
rigidity in the three rotational degrees of freedom and the two
translational degrees, but permitting free movement in the vertical
direction. FIG. 5 shows that radial differential expansion between
the floating steam header assembly 70 and the member 82 portion of
the cover assembly 72 is not restrained.
Sealing means, indicated generally at 98, FIG. 4, are interposed
between the free floating steam header assembly 70 and the cover
assembly 72. As best seen in FIGS. 6-9, this sealing means
comprises a first pair of sealing rings including a lower ring 100
and an upper ring 102 which are mounted for engagement with the
header assembly 70, and a second pair of sealing rings comprising a
lower ring 104 and an upper ring 106 which are mounted for
engagement with the cover assembly 72. The sealing rings are in the
form of segments and are provided with alignment pins 108, FIG. 8,
for keeping the ring halves in horizontal alignment. As best seen
in FIG. 7, the rings are provided with tapped holes 110 for removal
by means of a threaded bar 112. A first segmented retainer 114,
FIGS. 6 and 9, retains the sealing rings in vertical position and a
second segmented retainer 116 retains the first retainer in
position. It will be appreciated that the sealing means 98 may be
removed without disturbing the tubes. In addition, the sealing
means permits free radial and vertical movement of the steam
header.
It will be appreciated that the water header assembly 34, FIG. 1,
could also be constructed in a manner substantially the same as the
steam header assembly described in connection with FIGS. 4-9 to
permit differential expansion between the water header assembly and
the cover of the vessel.
It will thus be seen that the present invention does indeed provide
an improved heat exchanger which is superior in simplicity, economy
and efficiency as compared to prior art devices.
Although certain particular embodiments of the invention are herein
disclosed for purposes of explanation, various modifications
thereof, after study of the specification will be apparent to those
skilled in the art to which the invention pertains.
* * * * *