U.S. patent application number 14/108859 was filed with the patent office on 2014-04-17 for heat regenerator.
This patent application is currently assigned to SAIPEM S.A.. The applicant listed for this patent is Commissariat A L'Energie Atomique Et Aux Energies Alternatives, SAIPEM S.A.. Invention is credited to Tristan DESRUES, Jean-Francois FOURMIGUE, Philippe MUGUERRA, Jacques RUER.
Application Number | 20140102663 14/108859 |
Document ID | / |
Family ID | 46508103 |
Filed Date | 2014-04-17 |
United States Patent
Application |
20140102663 |
Kind Code |
A1 |
RUER; Jacques ; et
al. |
April 17, 2014 |
HEAT REGENERATOR
Abstract
A heat regenerator comprising at least one matrix made of a
refractory material, to ensure the storage and recovery of heat.
The matrix includes at least one through-channel capable of
enabling the circulation of a fluid, said channel comprising at
least two projections projecting into the space defined by said
channel, said projections being positioned on two opposite surfaces
of the channel.
Inventors: |
RUER; Jacques; (Fourqueux,
FR) ; MUGUERRA; Philippe; (Saint Cyr L'Ecole, FR)
; FOURMIGUE; Jean-Francois; (Fontaine, FR) ;
DESRUES; Tristan; (Saint Pancrasse, FR) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
SAIPEM S.A.
Commissariat A L'Energie Atomique Et Aux Energies
Alternatives |
Montigny Le Bretonneux
Paris |
|
FR
FR |
|
|
Assignee: |
SAIPEM S.A.
Montigny Le Bretonneux
FR
Commissariat A L'Energie Atomique Et Aux Energies
Alternatives
Paris
FR
|
Family ID: |
46508103 |
Appl. No.: |
14/108859 |
Filed: |
December 17, 2013 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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PCT/FR2012/051451 |
Jun 25, 2012 |
|
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14108859 |
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Current U.S.
Class: |
165/10 |
Current CPC
Class: |
F28D 17/02 20130101;
F28D 20/00 20130101; Y02E 60/14 20130101; F28F 3/04 20130101 |
Class at
Publication: |
165/10 |
International
Class: |
F28D 20/00 20060101
F28D020/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 27, 2011 |
FR |
11.55719 |
Claims
1. A heat regenerator comprising at least one matrix made of a
refractory material, in order to ensure the storage and recovery of
heat, said matrix comprising at least one through channel allowing
the circulation of a fluid, said channel comprising at least two
projections projecting into the volume defined by said channel,
said projections being positioned on two opposite surfaces of the
channel, the at least two projections being spaced apart by a
distance P between projections from 1 to 5 tunes the channel
length.
2. The heat regenerator of claim 1, wherein the volume defined by
the at least one channel amounts to from 30 to 50% of the total
matrix volume.
3. The heat regenerator of claim 1, wherein the channel has a
rectangular or square cross-section.
4. The heat regenerator of claim 3, wherein width b of the channel
is in the range between 4 and 15 millimeters, and in that length L
of the channel is in the range between 4 and 15 millimeters.
5. The heat regenerator of claim 1, wherein it comprises at least
two substantially parallel channels separated from each other by a
distance c between 2 and 15 millimeters, advantageously equal to 4
millimeters.
6. The heat regenerator of claim 1, wherein it comprises at least
one channel having a height R in the range between 5 and 50
meters.
7. A use of the heat regenerator of claim 1 in a heat storage and
recovery installation comprising at least one fluid admission
orifice.
8. The heat storage and recovery installation of claim 7, wherein
the lateral surfaces of the regenerator are thermally
insulated.
9. The heat storage and recovery installation of claim 8, wherein
it comprises a grid interposed between the fluid admission orifice
and the opening of the regenerator channels.
Description
FIELD OF THE INVENTION
[0001] The invention relates to a heat regenerator enabling to
store and to recover heat.
[0002] One of the fields of use of the present invention especially
relates to installations enabling to store electric or solar energy
in the form of heat.
BACKGROUND
[0003] The short-, medium, or long-term storage of significant
quantities of energy is a major issue, which has given rise to
numerous studies relative, in particular, to the storage of
electricity in the form of thermal energy.
[0004] For this purpose, regenerators are currently used to
temporarily store heat prior to its use in various applications.
Typically, heat regenerators comprise enclosures where heat can be
stored by heat transfer between a fluid such as smoke and the
material of the elements forming the enclosures. These solid
structures are crossed by channels through which smoke can
circulate. The cross-section of these channels may vary according
to the nature of the smokes, from a few millimeters to several tens
of centimeters. Indeed, in the case of the recovery of heat
conveyed by flue gases, the gases originating from dirty processes
(glass furnaces, blast furnaces) require channels having a larger
cross-section than gases originating from relatively clean
processes such as gas turbines.
[0005] Regenerators are generally defined according to the
following parameters: [0006] the maximum heat storage capacity.
This parameter is linked to the mass and to the physical properties
of the material forming the enclosures or matrixes, and to the
difference between the hot temperature and the cold temperature of
operation of the regenerator; [0007] the characteristic cycle time,
which depends on the thickness of the solid partitions and of the
channels forming the matrixes; [0008] the thermal performance, that
is, the ratio of the real storage capacity of the regenerator to
its maximum capacity, which depends on the thermal transfer
performance between the fluid and the matrix.
[0009] Document FR 2916101 describes an electric energy storage
method implementing the transformation of electric energy into heat
stored in two enclosures of heat regenerator type. It comprises a
thermodynamic cycle of heat pump type in storage mode, and of heat
engine type in recovery mode, using argon as a fluid. This device
causes practically no head loss during the fluid circulation and
the heat exchange. The operating constraints due to such an
electric energy storage installation imply storage/recovery times
of a few hours and fast response times for the materials. In this
device, the fluid crosses the regenerator via channels having a
constant cross-section along their entire height. Such channels
comprise no projections.
[0010] Generally, three parameters can enable to improve the
efficiency of a regenerator: [0011] the physical properties of the
material storing thermal energy. It is the product of the density
of the material by its specific heat. Generally, the optimal
properties correspond to relatively expensive materials. [0012] the
porosity of the material storing thermal energy, that is, the
volume left to the fluid within this material. [0013] the thermal
performance of the material storing thermal energy. This enables to
promote an optimal use of the maximum storage capacity of the
material.
[0014] The object of the present invention falls within the
framework of this last point relative to the improvement of heat
exchanges. Further, the device developed by the Applicant also
enables to considerably decrease the dimensions of heat
regenerators.
BRIEF DESCRIPTION OF THE INVENTION
[0015] The present invention relates to a heat regenerator capable
of being used in heat storage/recovery processes. It particularly
enables to decrease the volume of regenerators while providing the
same storage capacity as prior art regenerators.
[0016] More specifically, the present invention relates to a heat
regenerator comprising at least one matrix made of a refractory
material, in order to ensure the storage and recovery of heat, said
matrix comprising at least one through channel allowing the
circulation of a fluid, said channel comprising at least two
projections projecting into the volume defined by said channel.
[0017] Said projections are positioned on two opposite surfaces of
the channel.
[0018] Generally, the refractory material has a density
advantageously in the range between 2,000 and 10,000
kg/m.sup.3.
[0019] Advantageously, the at least one channel is formed of a
succession of repeated patterns, whereby the projections are
preferably arranged at fixed intervals in the fluid circulation
direction within the channel.
[0020] The regenerator according to the invention may comprise many
discretized elements in the form of bricks and forming the matrix
of refractory material, said bricks being crossed by at least one
channel comprising at least one projection projecting into the
volume defined by said channel.
[0021] The regenerator according to the invention may comprise
several identical reference bricks to keep the periodicity of the
projections within the channel(s), said bricks being adjacent to
one another to optimize the density of material without creating
spaces. The regenerator may further comprise a stack of bricks. The
stacking of the brick patterns is performed so that the channels
are aligned with one another, to avoid altering the fluid
circulation. Further, the brick may have a square, rectangular,
hexagonal, or cylindrical cross-section. It will be within the
abilities of those skilled in the art to determine means for
advantageously attaching the bricks together.
[0022] "Projection" means that the channel is not through in its
entire cross-section along its entire length. The channel thus
comprises at least two internal structures which obstruct part of
its cross-section at least along part of its height. Said
projections are made of a material identical to that of the matrix,
and thus of the brick. They are advantageously integral with the
matrix. In other words, in the brick or the matrix, the channel and
the projections advantageously form a unit element. Indeed, it is
important for the projections to be in contact with the
heat-storing brick to allow a transfer of the heat received by the
projections to the larger mass of the matrix.
[0023] The projection may be parallelepipedal, and in particular
have one dimension advantageously identical to the width of the at
least one channel of the matrix or of the brick.
[0024] Advantageously, the main dimension of the parallelepiped,
and for example its length, is directed parallel to the fluid
circulation direction, and thus to the main axis of the
channel.
[0025] The projections may also be trapezoidal, the longer side of
said trapezoid being confounded with the lateral wall of the
channel. Here again, one of the dimensions of the trapezoid is
advantageously identical to the channel width.
[0026] The projections present inside of the channels intensify
heat transfers between the matrix and the fluid without for all
this significantly altering the circulation of said fluid. Indeed,
considering the configuration of the channels and of the
projections according to the present invention, a low head loss is
desired over the entire regenerator. "Head loss" means the pressure
difference between the fluid pressure at the inlet of the
regenerator and the fluid pressure at its outlet, and thus after
having crossed the matrix. In other words, it designates the head
loss after the fluid has passed through the regenerator, which may
comprise a matrix of several bricks.
[0027] The projections enable to create turbulence by disturbing
the fluid circulation, and thus to intensify heat transfers.
Indeed, in the case of a circulation in a channel comprising no
projections, the only way to increase the heat exchange is to
decrease the hydraulic diameter of the channel, thus resulting in
channel continuity issues all along the height of the brick stack.
Thus, the projections of the invention generate high-speed areas,
direction change areas, and recirculation areas appear. Pressures
losses are intensified as a consequence of the creation of such
turbulence.
[0028] According to a preferred embodiment, and to optimize the
compactness of the regenerator relative to its thermal performance,
the volume occupied by the fluid is in the range from 30 to 50% of
the total volume of the matrix. It is the vacuum volume of the
matrix, except for the volume of the pores of the refractory
material, when said material comprises pores.
[0029] When the volume occupied by the fluid is smaller than 30%,
the solid mass is very large, and provides the matrix with a
maximum energy storage capacity. However, heat transfers are more
difficult and the real capacity in operation is much lower than
this maximum value.
[0030] When the volume occupied by the fluid is greater than 50%,
the compactness of the regenerator and thus of the enclosure
containing it is insufficient, and by all means incompatible with
the envisaged applications.
[0031] The channel(s) may advantageously have a rectangular or
square cross-section. In this specific case, the channel width is
preferably in the range between 4 and 15 millimeters, and its
length is preferably in the range between 4 and 15 millimeters. The
channel height depends on the regenerator height and thus on the
quantity of energy to be stored.
[0032] Advantageously, the regenerator height is between 5 and 50
meters. The matrix and the channel may have a height between 5 and
50 meters.
[0033] As already mentioned, the channel comprises at least two
projections advantageously positioned to be shifted in the fluid
circulation direction and thus along the channel height, one of the
projections being positioned on a first surface of the channel, and
the other on a second opposite surface of the channel. More
advantageously still, the channel comprises two projections
respectively positioned on two opposite surfaces of the channel, so
as to be shifted with respect to each other, in the general fluid
flow direction within the channel.
[0034] According to the invention, there is a plurality of
projections along a channel crossing the regenerator,
advantageously more than 100.
[0035] "Channel" also means the channel formed when two bricks are
stacked. The channel runs all throughout the matrix height.
[0036] According to an advantageous embodiment, when the brick or
the regenerator comprises at least two channels, the latter are
substantially parallel. Further, the channels are advantageously
separated by a distance between channels in the range between 2 and
15, more advantageously still equal to 4 millimeters.
[0037] According to a specific embodiment, in the case where the
heat regenerator comprises at least two adjacent bricks, the
distance between the channels of a first brick and the channels of
a second brick is preferably in the range from 2 to 15 millimeters,
and more advantageously still equal to 4 millimeters.
[0038] In a preferred embodiment, the heat regenerator has one and
the same inter-channel distance between channels of a same brick
and between channels of two different bricks, the bricks being
adjacent.
[0039] The distance between channels depends on the storage and
recovery time, given that the entire matrix thickness has to rise
from the cold temperature to the hot temperature, and conversely.
If the thickness is too large, a temperature gradient appears
between the surface and the core of the matrix. In this case, the
storage capacity decreases, since the refractory material cannot
achieve a complete cycle between the two operating temperatures. If
the thickness is too low, there is not enough refractory material
to store the thermal energy.
[0040] Typically, the internal projections extend across the entire
width of the channel when it has a square or rectangular
cross-section. In the case of a cylindrical channel, the
projections advantageously extend on one quarter of the perimeter
of the channel cross-section. The height of the projections
advantageously amounts to from 5 to 50% of the channel dimension
along which they are directed. The ratio of the height of the
projections to the channel length is advantageously between 0.05
and 0.5, and more advantageously between 25% and 35%.
[0041] It should be noted that the two dimensions do not extend
along the same direction. Further, in the regenerator according to
the invention, distance P between two successive projections on a
same side of a channel wall advantageously amounts to between one
and five times the length of channel L. Advantageously, distance P
between projections is constant along the entire height of the
channel crossing the matrix and the regenerator, thus creating a
repetitive channel portion pattern, repeated along the entire
height of the matrix and of the regenerator. It should also be
noted that distance P between projections comprises the length of a
projection.
[0042] Thus, according to a development of the invention, the
regenerator comprises a matrix comprising a plurality of through
channels, each channel being provided with a plurality of
projections respectively originating from a first wall and from the
wall opposite to the first wall of a channel, each projection being
spaced apart from the next one by a fixed distance P to form a
projection pattern repeated along the channel, along the
regenerator height.
[0043] "Plurality of channels" means from 10 to 100,000 channels,
especially from 100 to 10,000 channels.
[0044] The length of the projections along the fluid circulation
direction, that is, along the regenerator height, is adjusted to
obtain a geometric shape adapted to the manufacturing process,
while providing a sufficient contact surface area between the
projections and the channel wall to transfer the heat exchanged by
conduction. It advantageously is in the order of the channel
width.
[0045] Advantageously, the brick and the projections are made of a
non-porous refractory material, advantageously of ceramic based on
aluminum or cordierite ceramic.
[0046] Further, the non-porous refractory material advantageously
has no or almost no porosity, preferably below 5%.
[0047] The present invention also relates to the use of a heat
regenerator such as described hereabove in a heat storage and
recovery installation comprising at least one fluid admission
orifice. Further, the invention also relates to a heat storage and
recovery installation comprising at least one heat regenerator such
as described hereabove. Said heat may advantageously originate from
electric power or from concentrating solar power.
[0048] In a particularly preferred embodiment, in said heat storage
and recovery installation, at least the lateral portions and the
bottom of the heat regenerator are covered with a thermal insulator
layer.
[0049] This installation may further comprise a grid interposed
between the fluid inlet portion and the openings of the channels of
the heat regenerator. Said grid provides a better distribution of
the fluid between the channels.
[0050] In a preferred embodiment, the heat regenerators according
to the present invention are used in a method for storing electric
power in the form of heat involving a perfectly clean neutral gas
rather than fouling and corrosive flue gases, such as are likely to
come out of blast furnaces or of glass furnaces. Thus, the use of a
neutral gas such as argon as a fluid enables to decrease the
dimensions of the bricks of the heat regenerator.
[0051] Further, the heat regenerator which is the object of the
present invention may be formed according to a brick manufacturing
process such as previously described, according to shaping methods
known by those skilled in the art, by casting in a mold or by
pressing of a basic component. Several bricks may then be assembled
to form a heat regenerator.
[0052] In the context of the invention, it will be within the
abilities of those skilled in the art to adapt the dimensions of
the brick and of the regenerator, but also the dimensions of the
channels and of the projections according to the fluid temperature,
to the storage time, and to the amount of energy to be stored.
DESCRIPTION OF THE DRAWINGS
[0053] The invention and the resulting advantages will better
appear from the following non-limiting drawings and examples,
provided as an illustration of the invention.
[0054] FIG. 1A illustrates a brick comprising four through channels
according to the invention.
[0055] FIG. 1B illustrates a channel portion crossing a matrix
portion of a regenerator according to the invention.
[0056] FIG. 2A illustrates a portion of a channel according to the
present invention, comprising two parallelepipedal internal
projections positioned on two opposite surfaces of the channel.
[0057] FIG. 2B also illustrates a portion of a channel according to
the present invention, comprising two trapezoidal internal
projections positioned on two opposite surfaces of the channel.
[0058] FIG. 3 shows a portion of a channel according to a specific
embodiment of the present invention, comprising two internal
projections.
[0059] FIG. 4 shows the graph corresponding to the head loss
observed during the circulation of a fluid in a regenerator of
height R according to the invention, according to the ratio of
distance P between projections of the regenerator to the
regenerator length (L) according to FIG. 3.
[0060] FIG. 5 shows the graph obtained by plotting the Nusselt
number according to the channel geometry, and especially to the
ratio of distance P between projections of the regenerator and the
regenerator length (L).
[0061] FIG. 6 illustrates a heat storage enclosure comprising a
regenerator according to the invention.
DETAILED DESCRIPTION
[0062] Brick 1 of refractory material shown in FIG. 1A comprises
four parallel through channels 2. The channels emerge on either
side at the upper surface and at the lower surface of brick 1.
Channels 2 are characterized by their width b, their length L, and
their height R. Said channels are spaced apart by a distance c
along a first direction and a distance c' along a second direction
perpendicular to the first one. Distances c and c' between channels
are advantageously identical.
[0063] Of course, brick 1 may comprise a single channel or a
plurality of channels without departing from the scope of the
invention.
[0064] FIG. 1B schematically shows a portion of the matrix of the
regenerator crossed by a channel.
[0065] FIGS. 2A and 2B schematically show in perspective view two
channels 2 of rectangular cross-section according to the invention.
The fluid circulation direction within these channels has been
shown by arrows. The arrow direction indicates either a storage, or
an extraction.
[0066] The channel of FIG. 2A comprises two parallelepipedal
projections 3 of same width than that of channel 2, but having a
height h smaller than its length, to avoid obstructing it. Thus,
lateral surfaces 7 of projection 3 define a 90.degree. angle with
the channel wall in contact with the projection or from which it
projects. Longitudinal surface 8 of projection 3 is perpendicular
to lateral surfaces 7 of said projection and extends along the
channel height, that is, in the fluid circulation direction.
[0067] The two projections 3 have a substantially identical shape,
but are shifted from each other and also project from two opposite
surfaces of the channel
[0068] The channel of FIG. 2B has two trapezoidal projections 3.
The principle is identical to that of FIG. 2A. In the case in
point, the longer side of the trapezoid is confounded with the
lateral wall of the channel from which projection 3 projects.
[0069] In this specific case, although the disturbance to the fluid
circulation generated by the projections is lower than that of the
channel of FIG. 2A, it however provides an efficient heat transfer,
improved with respect to prior art.
[0070] Channel 2 illustrated in FIG. 3 comprises two cubic
projections 3 of height h and of width b. Lateral surfaces 7 of the
projections define a straight angle with the channel wall in
contact with the projection or from which it projects. The channel
is further characterized by its length L and P, the distance
between two successive projections on a same side. As illustrated
in FIG. 3, distance P between projections comprises the length of a
projection. The length of the projection is defined by the length
of the surface in contact with the channel, according to the fluid
circulation direction, which direction is indicated by an arrow in
FIG. 3. Further, to better show distance P between projections,
projection 3 of a stacked channel is shown in dotted lines.
[0071] FIG. 6 shows a heat storage enclosure comprising a heat
regenerator according to the invention. The regenerator comprises,
in particular, an assembly of bricks 1, having their lateral
portions, in the channel height direction, covered with a thermal
insulator layer 4. Thermal insulator layer 4 enables to limit
energy losses towards the outside of the regenerator between
storage and recovery areas.
[0072] Although, for clarity, this has not been shown in FIG. 6,
channels 2 comprise projections projecting into the volume defined
by said channels. The regenerator comprises in the described
example 35 parallel channels, all separated by an identical
distance c.
[0073] Further, two fluid inlets 6 enable the fluid to penetrate
and to be discharged from the enclosure comprising the bricks.
After it has been introduced into the enclosure, the fluid is
distributed in the channels after having been distributed through a
grid 5, installed between fluid inlet 6 and bricks 1. Grid 5 has a
multiplicity of through openings ensuring a homogeneous
distribution of the fluid.
[0074] "Fluid inlet" also designates a fluid outlet or discharge
port.
EXAMPLES OF EMBODIMENT
[0075] The heat regenerator according to the present invention
advantageously enables to store a quantity of electric energy in
the range between 1 and 100 GW.h.sup.-1 for a storage time between
2 and 6 hours. Further, from 60 to 70% of the energy is
recovered.
[0076] The regenerators of examples A and B comprise a stack of
adjacent identical bricks. The bricks comprise at least one through
channel.
[0077] The channels have the following dimensions: [0078] height
R=10 meters; [0079] width b=6 mm; [0080] length L=12 mm [0081]
distance c between channels=4 mm. [0082] height of projection h=3.5
mm.
Regenerator A (Prior Art)
[0083] In the case of an installation having a 100-MW power and a
600-MWh capacity, heat regenerator A according to prior art (FR
2916101) comprises two enclosures for which the brick volume is
11,100 m.sup.3, and straight channels. The volume defined by the
channels is equal to 4,900 m.sup.3, that is, approximately 44% of
the total volume defined by the bricks. The volume defined by the
material forming the enclosures is equal to 6,200 m.sup.3, that is,
approximately 56% of the total volume defined by the bricks.
Regenerator B (Invention)
[0084] For an installation having the same characteristics, the
heat regenerator according to the invention comprises two
enclosures with a 6,900-m.sup.3 brick volume, and straight channels
comprising projections projecting into the volume defined by said
channels. The vacuum volume defined by the channels is equal to
2,700 m.sup.3, that is, approximately 39% of the total volume
defined by the bricks. The volume defined by the material forming
the enclosures and the projections is equal to 4,200 m.sup.3, that
is, approximately 61% of the total volume defined by the
bricks.
[0085] The present invention thus enables to optimize the enclosure
geometry and in particular to decrease their volume by close to 38%
in this case. Such modifications thus enable to decrease the
quantity of material used and manufacturing costs.
Head Loss According to Ratio P/L
[0086] The fluid undergoes a head loss .DELTA.P after having
circulated through a regenerator according to the invention having
a height R of 10 m.
[0087] It is typically admitted that in such conditions, a pressure
loss lower than or equal to 0.1 bar remains acceptable.
[0088] In the context of the invention, a head loss of 0.1 bar for
a ratio P/L of 1.70 corresponds to a Nusselt number greater than
13. This value reflects the amplification of the heat exchange due
to the turbulence created by the projections. Indeed, in the case
of a channel of similar dimensions but having no projections, the
obtained Nusselt number is equal to 3.4.
* * * * *