U.S. patent application number 14/867905 was filed with the patent office on 2016-04-21 for heat exchanger.
The applicant listed for this patent is ROLLS-ROYCE POWER ENGINEERING PLC. Invention is credited to Heather DAVIES, Susana LOPEZ RAMIREZ, Nickolaos PILATIS, Daniel ROBERTSON, Guan-Wei TSANG, Daniel WALTON.
Application Number | 20160109189 14/867905 |
Document ID | / |
Family ID | 54207400 |
Filed Date | 2016-04-21 |
United States Patent
Application |
20160109189 |
Kind Code |
A1 |
DAVIES; Heather ; et
al. |
April 21, 2016 |
HEAT EXCHANGER
Abstract
A plate-fin heat exchanger for transferring heat from hot
low-pressure fluid to cold high-pressure fluid may include a
plurality of adjacent heat exchange modules, each having a
plurality of plates and fins that define hot fluid flow paths and
cold fluid flow paths. A first entry manifold delivers hot fluid to
each of the hot fluid flow paths and a second entry manifold
delivers cold fluid to each of the cold fluid flow paths. A first
exit manifold is provided for receiving hot fluid from each of the
hot fluid flow paths and a second exit manifold is provided for
receiving cold fluid from each of the cold fluid flow paths. The
first entry manifold includes two inlets through which hot fluid
can enter the heat exchanger, and the first exit manifold includes
two outlets through which the hot fluid can exit the heat
exchanger.
Inventors: |
DAVIES; Heather; (Widnes,
GB) ; PILATIS; Nickolaos; (Warrington, GB) ;
ROBERTSON; Daniel; (Derby, GB) ; WALTON; Daniel;
(Derby, GB) ; TSANG; Guan-Wei; (Liverpool, GB)
; LOPEZ RAMIREZ; Susana; (Manchester, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ROLLS-ROYCE POWER ENGINEERING PLC |
Derby |
|
GB |
|
|
Family ID: |
54207400 |
Appl. No.: |
14/867905 |
Filed: |
September 28, 2015 |
Current U.S.
Class: |
165/173 |
Current CPC
Class: |
F28F 9/0243 20130101;
F28F 3/02 20130101; F28D 9/0037 20130101; F28D 2021/0054 20130101;
F28F 9/02 20130101; F02C 1/05 20130101 |
International
Class: |
F28F 3/02 20060101
F28F003/02; F28F 9/02 20060101 F28F009/02 |
Foreign Application Data
Date |
Code |
Application Number |
Oct 17, 2014 |
GB |
1418403.0 |
Oct 17, 2014 |
GB |
1418404.8 |
Claims
1. A plate-fin heat exchanger for transferring heat from a hot low
pressure fluid to a cold high pressure fluid, the heat exchanger
comprising: a plurality of adjacent heat exchange modules, each
heat exchange module comprising a plurality of plates and fins that
define a plurality of hot fluid flow paths and a plurality of cold
fluid flow paths; a first entry manifold for delivering hot fluid
to each of the plurality of the hot fluid flow paths and a second
entry manifold for delivering cold fluid to each of the plurality
of cold fluid flow paths; a first exit manifold for receiving hot
fluid from each of the plurality of hot fluid flow paths and a
second exit manifold for receiving cold fluid from each of the
plurality of cold fluid flow paths; wherein the first entry
manifold comprises two inlets through which hot fluid can enter the
heat exchanger and the first exit manifold comprises two outlets
through which the hot fluid can exit the heat exchanger.
2. The heat exchanger according to claim 1, wherein the heat
exchange modules are adjacently stacked and arranged such that the
axial length of the heat exchanger is at least twice the height of
the heat exchanger.
3. The heat exchanger according to claim 1, wherein each manifold
extends from one axial end of the heat exchanger to the opposite
axial end of the each exchanger so as to connect to each of the
corresponding plurality of hot or cold fluid flow paths.
4. The heat exchanger according to claim 1, wherein one inlet is at
an axial end of the first entry manifold and the other inlet is at
the opposite axial end of the first entry manifold.
5. The heat exchanger according to claim 1, wherein one outlet is
at an axial end of the first exit manifold and the other outlet is
at the opposite axial end of the first exit manifold.
6. The heat exchanger according to claim 1, wherein the second
entry manifold comprises a single inlet through which cold fluid
can enter the second entry manifold and the second exit manifold
comprises a single outlet through which the cold fluid can exit the
second exit manifold.
7. The heat exchanger according to claim 6, wherein the inlet of
the second entry manifold and the outlet of the second exit
manifold are provided on the same axial end of the heat
exchanger.
8. The heat exchanger according to claim 1, wherein the cross
sectional area of the second inlet manifold and/or the second
outlet manifold is larger than the cross sectional area of the
first inlet manifold and/or the first outlet manifold.
9. The heat exchanger according to claim 1, wherein the axial
length of the heat exchanger is at least four times the width of
the heat exchanger.
10. The heat exchanger according to claim 1, wherein each entry and
exit manifold is accommodated partially within a region defined by
the modules and extends partially outside a region defined by the
modules.
11. The heat exchanger according to claim 1, wherein the entry and
exit manifolds define a cylindrical tube.
12. The use of the heat exchanger according to claim 1, wherein the
hot low pressure fluid is liquid sodium and the cold high pressure
fluid is nitrogen gas.
13. A nuclear reactor plant comprising the heat exchanger according
to claim 1.
14. The nuclear reactor plant according to claim 13, wherein the
nuclear reactor plant is a sodium fast reactor plant.
15. A plate-fin heat exchanger for transferring heat from a hot low
pressure fluid to a cold high pressure fluid, the heat exchanger
comprising: a plurality of adjacent heat exchange modules, each
heat exchange module comprising a plurality of plates and fins that
define a plurality of hot fluid flow paths and a plurality of cold
fluid flow paths; a first entry manifold for delivering hot fluid
to each of the plurality of the hot fluid flow paths and a second
entry manifold for delivering cold fluid to each of the plurality
of cold fluid flow paths; a first exit manifold for receiving hot
fluid from each of the plurality of hot fluid flow paths and a
second exit manifold for receiving cold fluid from each of the
plurality of cold fluid flow paths; wherein the heat exchange
modules are adjacently stacked and arranged such that the axial
length of the heat exchanger is at least twice the height of the
heat exchanger.
16. A plate-fin heat exchanger for transferring heat from a hot low
pressure fluid to a cold high pressure fluid, the heat exchanger
comprising: a plurality of adjacent heat exchange modules, each
heat exchange module comprising a plurality of plates and fins that
define a plurality of hot fluid flow paths and a plurality of cold
fluid flow paths; a first entry manifold for delivering hot fluid
to each of the plurality of the hot fluid flow paths and a second
entry manifold for delivering cold fluid to each of the plurality
of cold fluid flow paths; a first exit manifold for receiving hot
fluid from each of the plurality of hot fluid flow paths and a
second exit manifold for receiving cold fluid from each of the
plurality of cold fluid flow paths; wherein the modules comprise a
recess in each corner thereof for partially accommodating one of
the manifolds, such that a portion of each manifold is accommodated
within a region defined by the modules and a portion of each
manifold is outside a region defined by the modules.
Description
FIELD OF INVENTION
[0001] The present invention relates to a heat exchanger, in
particular but not exclusively a heat exchanger for a nuclear
reactor plant.
BACKGROUND
[0002] Typically, a nuclear power plant includes a nuclear core, a
heat exchanger, a turbine and a condenser. A primary fluid is
circulated to the core where the primary fluid cools the core and
in the process is heated. The heated primary fluid is then directed
to a hot side of the heat exchanger. A secondary fluid is directed
to a cold side of the heat exchanger and heat is transferred from
the primary fluid to the secondary fluid. Upon exiting the heat
exchanger the secondary fluid is directed to the turbine. The
turbine is generally connected to a generator to generate
electricity.
[0003] Generally, to deal with the heat transfer requirements of a
nuclear power plant, the heat exchanger is usually of the shell and
tube type. The primary or the secondary fluid may be directed
through the tubes and the secondary or primary fluid may be
directed around the tubes within the shell. The walls of the tubes
provide a barrier to reduce the risk of the primary fluid
contaminating the secondary fluid. The shell and tube heat
exchangers are generally extremely large; for example in some
applications the height of the heat exchanger can be around 20
m.
[0004] In non-nuclear applications, other types of heat exchangers
are used. For example a plate-fin type heat exchanger. An example
of such a heat exchanger used in the oil and gas industry is
described in WO92/15830. A plate-fin type heat exchanger includes a
plurality of stacked plates having fins that define a flow path for
hot and cold fluid. Generally, the heat exchanger will be arranged
so that the flow of hot fluid is adjacent (but separated by a
plate) to the flow of cold fluid for optimal heat transfer.
SUMMARY OF INVENTION
[0005] The present invention seeks to provide a more compact heat
exchanger suitable for a nuclear power plant.
[0006] A first aspect of the disclosure provides a plate-fin heat
exchanger for transferring heat from a hot low pressure fluid to a
cold high pressure fluid. The heat exchanger comprises a plurality
of adjacent heat exchange modules, each heat exchange module
comprising a plurality of plates and fins that define a plurality
of hot fluid flow paths and a plurality of cold fluid flow paths. A
first entry manifold is provided for delivering hot fluid to each
of the plurality of the hot fluid flow paths and a second entry
manifold is provided for delivering cold fluid to each of the
plurality of cold fluid flow paths. A first exit manifold is
provided for receiving hot fluid from each of the plurality of hot
fluid flow paths and a second exit manifold is provided for
receiving cold fluid from each of the plurality of cold fluid flow
paths. The heat exchange modules are adjacently stacked and
arranged such that the axial length of the heat exchanger is at
least twice the height of the heat exchanger.
[0007] The heat exchanger of the first aspect can be configured to
have increased thermal duty compared to a plate-fin heat exchanger
of the prior art having a similar volume.
[0008] The heat exchanger of the first aspect can be configured to
have a thermal duty suitable for a nuclear power plant.
[0009] The person skilled in the art understands that reference to
a hot fluid refers to a fluid that is relatively hotter than the
cold fluid, and reference to a cold fluid refers to a fluid that is
relatively colder than the hot fluid, as is conventional in the
art. Alternatively, the hot fluid may be referred to as the primary
fluid and the hot fluid flow path may be referred to as the primary
fluid flow path. The cold fluid may be referred to as the secondary
fluid and the cold fluid flow path may be referred to as the
secondary fluid flow path. Further alternatively, the hot fluid may
be considered a first fluid and the cold fluid may be considered a
second fluid, the first fluid being hotter than the second
fluid.
[0010] Reference to low pressure and high pressure refers to the
relative pressure of the hot and cold fluids. By way of example
only, the low pressure fluid may be at approximately atmospheric
pressure and the high pressure fluid may be at a pressure greater
than or equal to 100 bar, for example greater than or equal to 150
bar, for example between 150 bar and 200 bar.
[0011] Each manifold may extend from one axial end of the heat
exchanger to the opposite axial end of the heat exchanger so as to
connect to each of the corresponding plurality of hot or cold fluid
flow paths.
[0012] The first entry manifold may comprise two inlets through
which fluid can enter the entry manifold. The first exit manifold
may comprise two outlets through which the hot fluid can exit the
exit manifold.
[0013] The provision of two inlets and two outlets has been found
to improve the distribution of hot fluid in the heat exchanger
which in turn can improve the thermal duty of the heat exchanger.
The provision of two inlets and two outlets has been found to be
particularly beneficial when the length of the heat exchanger is
greater than or equal to two times the height of the heat
exchanger.
[0014] The entry and exit manifolds may include a plurality of
openings along the length thereof and aligned with the
corresponding plurality of hot or cold fluid flow paths.
[0015] One inlet may be at an axial end of the first entry manifold
and the other inlet may be at the opposite axial end of the first
entry manifold.
[0016] One outlet may be at an axial end of the first exit manifold
and the other outlet may be at the opposite axial end of the first
exit manifold.
[0017] The second entry manifold may comprise a single inlet
through which cold fluid can enter the second entry manifold. The
second exit manifold may comprise a single outlet through which the
cold fluid can exit the second exit manifold.
[0018] The inlet of the second entry manifold and the outlet of the
second exit manifold may be provided on the same axial end of the
heat exchanger.
[0019] The axial end of the second entry manifold opposite the
inlet may be capped. The axial end of the second exit manifold
opposite the outlet may be capped.
[0020] The cross sectional area of the second inlet manifold may be
larger than the cross sectional area of the first inlet manifold.
The cross sectional area of the second outlet manifold may be
larger than the cross sectional area of the first outlet
manifold.
[0021] The axial length of the heat exchanger may be at least four
times the width of the heat exchanger.
[0022] The axial length of the heat exchanger may be equal to or
between two and four times the height of the heat exchanger. The
axial length of the heat exchanger may be at least three times the
width of the heat exchanger.
[0023] The heat exchanger may comprise equal to or more than 10
modules, for example equal to or more than 15 modules or equal to
or more than 18 modules. Each module may comprise 15 to 30 cold
fluid flow paths and 15 to 30 hot fluid flow paths.
[0024] Each entry and exit manifold may be accommodated partially
within a region defined by the modules and extends partially
outside a region defined by the modules.
[0025] For example, each manifold may comprise a recess in each
corner that is shaped and dimensioned to accommodate a portion of
the manifold.
[0026] The entry manifolds may be positioned in an upper region of
the heat exchanger and the exit manifold may be positioned in a
lower region of the heat exchanger. The first entry manifold may be
positioned in one corner of the modules and the first outlet
manifold may be positioned in a corner diagonally opposite the
first entry manifold. The second entry manifold may be positioned
in one corner of the modules and the second outlet manifold may be
positioned in a corner diagonally opposite the entry manifold.
[0027] The entry and exit manifolds may define a cylindrical
tube.
[0028] A second aspect of the disclosure provides a plate-fin heat
exchanger for transferring heat from a hot low pressure fluid to a
cold high pressure fluid. The heat exchanger may comprise a
plurality of adjacent heat exchange modules, each heat exchange
module comprising a plurality of plates and fins that define a
plurality of hot fluid flow paths and a plurality of cold fluid
flow paths. A first entry manifold is provided for delivering hot
fluid to each of the plurality of the hot fluid flow paths and a
second entry manifold is provided for delivering cold fluid to each
of the plurality of cold fluid flow paths. A first exit manifold is
provided for receiving hot fluid from each of the plurality of hot
fluid flow paths and a second exit manifold is provided for
receiving cold fluid from each of the plurality of cold fluid flow
paths. The first entry manifold comprises two inlets through which
hot fluid can enter the heat exchanger and the first exit manifold
comprises two outlets through which the hot fluid can exit the heat
exchanger.
[0029] As will be appreciated by the person skilled in the art in
view of the disclosure of the present application, the heat
exchanger of the second aspect may have one or more optional
features of the heat exchanger of the second aspect.
[0030] A third aspect of the disclosure provides a plate-fin heat
exchanger for transferring heat from a hot low pressure fluid to a
cold high pressure fluid. The heat exchanger may comprise a
plurality of adjacent heat exchange modules, each heat exchange
module comprising a plurality of plates and fins that define a
plurality of hot fluid flow paths and a plurality of cold fluid
flow paths. A first entry manifold is provided for delivering hot
fluid to each of the plurality of the hot fluid flow paths and a
second entry manifold is provided for delivering cold fluid to each
of the plurality of cold fluid flow paths. A first exit manifold is
provided for receiving hot fluid from each of the plurality of hot
fluid flow paths and a second exit manifold is provided for
receiving cold fluid from each of the plurality of cold fluid flow
paths. The modules comprise a recess in each corner thereof for
partially accommodating one of the manifolds, such that a portion
of each manifold is accommodated within a region defined by the
modules and a portion of each manifold is outside a region defined
by the modules.
[0031] A fourth aspect of the disclosure provides a nuclear reactor
fin-plate heat exchanger for use in a sodium fast reactor
plant.
[0032] The inventors have gone against the prejudice in the art and
designed a fin-plate type heat exchanger of transferring heat from
a hot (or primary) fluid to a cold (or secondary) fluid in a
nuclear power plant.
[0033] A fifth aspect of the disclosure provides a use of the heat
exchanger according to the first and/or second aspect, wherein the
hot low pressure fluid is liquid sodium and the cold high pressure
fluid is nitrogen gas.
[0034] A sixth aspect of the disclosure provides a nuclear reactor
plant comprising the heat exchanger according to the first, second,
third and/or fourth aspects.
[0035] The nuclear reactor plant may be a sodium fast reactor
plant.
DESCRIPTION OF DRAWINGS
[0036] The invention will now be described, by way of example only,
with reference to the accompanying drawings in which:
[0037] FIG. 1 illustrates a schematic of a sodium fast reactor
nuclear power plant;
[0038] FIG. 2 illustrates a perspective view of a heat exchanger
suitable for use in the nuclear power plant of FIG. 1;
[0039] FIGS. 3 and 4 illustrate end views of the heat exchanger of
FIG. 2;
[0040] FIG. 5 illustrates a perspective view of two modules of the
heat exchanger of FIG. 2;
[0041] FIG. 6 illustrates a perspective view of two modules and a
manifold of the heat exchanger of FIG. 2;
[0042] FIG. 7 illustrates a cross sectional view through a
plate-fin arrangement of a module of FIG. 6;
[0043] FIG. 8 illustrate a fluid flow path of hot fluid through a
plate-fin arrangement of FIG. 7; and
[0044] FIG. 9 illustrates a fluid flow path of cold fluid through a
plate-fin arrangement of FIG. 7.
DETAILED DESCRIPTION
[0045] Referring to FIG. 1, a sodium fast reactor plant is
indicated generally at 10. The reactor plant includes a first
sodium circuit 13, a second sodium circuit 15 and a nitrogen gas
cycle 17. The first sodium circuit 13 includes a reactor core where
heat energy is generated. A first flow of liquid sodium is
circulated to the core for cooling. In the cooling process the
liquid sodium is heated. The first flow of liquid sodium is then
circulated from the core to a first heat exchanger 14 before being
circulated back to the core. The liquid sodium is circulated around
the first sodium circuit by a pump 16.
[0046] The second sodium circuit 15 includes a second flow of
liquid sodium. The second flow of liquid sodium is circulated to
the first heat exchanger 14 where heat is transferred from the
first flow of liquid sodium to the second flow of liquid sodium.
The second flow of liquid sodium then flows to a second or
intermediate heat exchanger 20 before being circulated back to the
first heat exchanger. The second flow of liquid sodium is
circulated around the second sodium circuit by a pump 18.
[0047] The nitrogen gas cycle 17 includes a flow of nitrogen gas.
The nitrogen gas is circulated to the intermediate heat exchanger
20 where heat is transferred from the second flow of liquid sodium
to the nitrogen. Nitrogen then flows from the heat exchanger to a
turbine 22. The turbine 22 is connected to a compressor 24 and an
electrical generator 26. Nitrogen gas flows from the turbine 22 to
a recuperator 28, then to a heat sink 30, before being directed to
the compressor 24. The nitrogen gas flows from the compressor to
the recuperator where the nitrogen gas is pre-heated before being
directed to the intermediate heat exchanger 20. In this way
electricity can be generated from a nuclear core.
[0048] The heat exchanger 20 will now be described in more detail
with reference to FIGS. 2 to 9.
[0049] The heat exchanger 20 is a plate-fin heat exchanger. The
heat exchanger includes a plurality of heat exchange modules 32.
The heat exchange modules are linearly arranged adjacent each
other. Each heat exchanger module is axially aligned with a
neighbouring heat exchange module.
[0050] In the present embodiment, each heat exchange module has a
height H greater than the width W. In the present embodiment the
height H is 1.2 to 1.6 times the width W. The heat exchange modules
are dimensioned and stacked such that the longitudinal length L of
the heat exchanger 20 is 3 to 5 times the width W of the heat
exchange modules. In the present embodiment 18 modules are
provided, but any suitable number may be provided. Furthermore,
different ratios of height H, width W and length L may be provided
than those described for the present embodiment.
[0051] As shown most clearly in FIGS. 8 and 9, each heat exchange
module defines a plurality of hot fluid flow paths 62 and a
plurality of cold fluid flow paths 60. The liquid sodium (which may
be referred to as the primary fluid) is circulated along the hot
fluid flow paths and the nitrogen gas (which may be referred to as
the secondary fluid) is circulated along the cold fluid flow paths.
The fluid flow paths will be described in more detail later.
[0052] Referring in particular to FIGS. 5 and 6, each module 32 has
a corner recess or cut-in 48, 50 so as to accommodate a portion of
a manifold 34, 35, 36 or 37. In the present embodiment the cross
section of each manifold is circular so the recesses are a circular
segment shape. As will be understood later with respect to the
description of the manifolds, two of the recesses 48 are larger
than the other two recesses 50.
[0053] Referring now to FIGS. 2 to 4, manifolds 34, 35, 36, 37 are
provided at each corner of the heat exchanger. Two entry manifolds
34, 36 and two exit manifolds 35, 37 are provided. The entry
manifolds 34, 36 are, in use, positioned at an upper end of the
heat exchanger and the exit manifolds 35, 37 are, in use,
positioned at a lower end of the heat exchanger. The entry manifold
for supplying the cold fluid to the cold fluid flow paths (referred
to from here-on-in as the cold entry manifold 34) and the exit
manifold for receiving the cold fluid from the cold fluid flow
paths (referred to from here-on-in as the cold exit manifold 37)
are at diagonally opposing corners. The entry manifold for
supplying the hot fluid to the hot fluid flow paths (referred to
from here-on-in as the hot entry manifold 36) and the exit manifold
for receiving the hot fluid from the hot fluid flow paths (referred
to from here-on-in as the hot exit manifold 35) are at diagonally
opposing corners.
[0054] The manifolds 34, 35, 36 and 37 are elongate and extend from
one axial end of the heat exchanger 20 to the opposing axial end of
the heat exchanger 20. In the present embodiment the manifolds have
a circular cross-section, e.g. they can be considered to be
substantially cylindrical tubes. However, in alternative
embodiments the manifolds may have any other suitable cross
section, e.g. oval. The cold entry manifold 34 and the cold exit
manifold 37 have a similar or equal diameter, and the hot entry
manifold 36 and the hot exit manifold 35 have a similar or equal
diameter. The cold entry and exit manifolds have a larger cross
section (e.g. a greater diameter) than the hot entry and exit
manifolds.
[0055] The entry and exit manifolds 34, 35, 36 and 37 include a
plurality of openings along the length thereof that are arranged to
align with the corresponding fluid flow path so that the entry and
exit manifolds are in fluid communication with the corresponding
cold or hot fluid flow paths 60, 62.
[0056] The cold entry manifold 34 includes a single inlet 38 and
the cold exit manifold 35 includes a single outlet 40. The inlet 38
and the outlet 40 of the cold manifolds are provided at one axial
end of the manifold and are provided on the same axial face of the
heat exchanger. The opposite axial ends of the cold manifolds are
closed off by a cap 42. In alternative embodiments the inlet and
the outlet may be provided at opposite axial ends of the heat
exchanger or provided at a position along the longitudinal length
of the manifold.
[0057] The hot entry manifold 36 includes two inlets 44 and the hot
exit manifold 37 includes two outlets 46. The inlets 44 and the
outlets 46 are provided at the axial ends of the manifold, e.g. on
the axial end faces of the heat exchanger. However, in alternative
embodiments the inlets and outlets 46 may be provided at any
position along the axial length of the manifold, but improved
results have been found when the inlets and outlets are provided at
or near the axial ends of the manifolds.
[0058] The fluid flow paths 60, 62 defined by the modules 32 are
shown in more detail in FIGS. 7 to 9. Each cold flow path 60 flows
from one of the openings in the cold inlet manifold to one of the
openings in the cold outlet manifold. Each hot flow path 62 flows
from one of the openings in the hot inlet manifold to one of the
openings in the hot outlet manifold. The fluid flow paths are
arranged so that each fluid flow path is substantially the same
length.
[0059] The modules 32 include a plurality of plates 54 and fins 56.
Various methods of forming fluid flow paths with plates and fins
are known in the art, but one example is illustrated in FIG. 7. As
shown in FIG. 7, plates are stacked with fins separating the plates
and forming channels 58. The channels 58 define the or at least
part of the fluid flow paths. In the presently described embodiment
the fins are connected to the plates using diffusion bonding and
the structure is formed using super plastic forming, similar to the
diffusion bonding super plastic forming method described in
WO92/15830 which is incorporated herein by reference.
[0060] In use, the inlets 44 of the hot entry manifold are
connected to receive a flow of liquid sodium from the first heat
exchanger 14 of the second sodium circuit 15, and the outlets 46 of
the hot exit manifold are connected to deliver a flow of liquid
sodium to the pump 18 to be circulated to the first heat exchanger
14. The inlet 38 of the cold entry manifold is connected to a flow
of gaseous nitrogen from the recouperator 28 of the nitrogen gas
cycle, and the outlet 40 of the cold exit manifold is connected to
deliver a flow of gaseous nitrogen to the turbine 22 of the
nitrogen gas cycle. By way of example only, the liquid sodium may
enter the heat exchanger 20 at a temperature exceeding 520.degree.
C. and at approximately atmospheric pressure. The liquid sodium may
exit the heat exchanger 20 at a temperature below 400.degree. C.
and at approximately atmospheric pressure. The gaseous nitrogen may
enter the heat exchanger 20 at a temperature below 370.degree. C.
and a pressure above 150 bar. The gaseous nitrogen may exit the
heat exchanger 20 at a temperature above 500.degree. C. and at a
pressure above 150 bar.
[0061] The described heat exchanger has been found to provide an
increased thermal duty compared to plate-fin heat exchangers of the
prior art. The described heat exchanger occupies a smaller volume
for a given thermal density than a U-tubed heat exchanger of the
prior art.
[0062] Several arrangements of heat exchangers were tested to
review the benefit of having two inlets and two outlets on the hot
fluid manifolds. Firstly, a similar arrangement of heat exchanger
as shown in FIG. 2 was used, but only one inlet was provided in the
hot entry manifold and only one inlet was provided in the hot exit
manifold, the inlets were positioned on the same axial end of the
heat exchanger. In this arrangement there was a large flow rate at
the axial end near the inlets, but this flow rate decreased towards
the opposite axial end of the heat exchanger (i.e. the end without
an inlet or outlet in the hot fluid manifolds). When a single inlet
was provided at one axial end of the heat exchanger and a single
outlet was provided at an opposite axial end of the heat exchanger,
a low flow rate was seen in a region near the inlet and a high flow
rate was seen in a region near the outlet. A further alternative
arrangement tested was to position the inlet and the outlet mid-way
between the axial ends of the heat exchanger. In this arrangement,
the flow rate was high in a central region of the heat exchanger
but much lower at axial ends of the heat exchanger. The described
example heat exchanger with two inlets and two outlets was found to
have reduced pressure losses and improved fluid distribution
compared to the tested arrangements. Reduced pressure losses and
improved fluid distribution can contribute to an increase in the
thermal duty of the heat exchanger.
[0063] The pressure drop of the cold fluid flowing through the heat
exchanger has been reduced by increasing the cross-sectional area
of the cold fluid manifolds. It is particularly beneficial to
reduce the pressure drop of the cold fluid because the cold fluid
flows to the turbine.
[0064] The pressure drop of the fluid flow in the heat exchanger
and the thermal duty of the heat exchanger has been found to be
optimised by accommodating part of the manifold in a region that
would otherwise be occupied by the modules and part of the manifold
outside of the modules. This is contrary to prior art arrangements
where the manifold is provided entirely outside the, usually
rectangular modules, (known in the art as an external manifold), or
the manifold is accommodated entirely within a region that would be
otherwise occupied by the modules (known in the art as an internal
manifold).
[0065] It will be appreciated by one skilled in the art that, where
technical features have been described in association with one or
more embodiments, this does not preclude the combination or
replacement with features from other embodiments where this is
appropriate. Furthermore, equivalent modifications and variations
will be apparent to those skilled in the art from this disclosure.
Accordingly, the exemplary embodiments of the invention set forth
above are considered to be illustrative and not limiting.
[0066] The flow through the heat exchanger has been described as a
counter-flow arrangement, but in alternative embodiments a
cross-flow or co-flow arrangement may be used.
[0067] The heat exchanger has been described as being used in a
sodium fast reactor, with sodium as the primary fluid and nitrogen
as the secondary fluid. However, in alternative embodiments the
heat exchanger may be used with an alternative reactor or in a
non-nuclear application. For example, the reactor may be a sodium
fast reactor having sodium as the primary fluid and water as the
secondary fluid. Further alternatively, the reactor may be a
pressurised water reactor, boiling water reactor, a molten salt
reactor, a gas cooled reactor or an alternative type of liquid
metal cooled reactor.
[0068] In alternative embodiments, the described heat exchanger may
form the first heat exchanger 14 or the recuperator 28 of the
sodium fast reactor plant shown in FIG. 1.
[0069] The primary and secondary fluid may be selected depending on
the reactor type or the relevant application, for example, the
primary and secondary fluid may both be water.
* * * * *