U.S. patent application number 13/575982 was filed with the patent office on 2012-11-22 for solar heat receiver.
This patent application is currently assigned to MITSUBISI HEAVY INDUSTRIES, LTD. Invention is credited to Kenji Atarashiya, Shigenari Horie, Kazuta Kobayashi, Manabu Maeda, Keiji Mizuta.
Application Number | 20120291772 13/575982 |
Document ID | / |
Family ID | 44355338 |
Filed Date | 2012-11-22 |
United States Patent
Application |
20120291772 |
Kind Code |
A1 |
Atarashiya; Kenji ; et
al. |
November 22, 2012 |
SOLAR HEAT RECEIVER
Abstract
Heat-receiving pipes of a heat receiver have portions having
high heat flux on at the side near an opening in a length direction
and extending to positions outside of a casing in a radial
direction. Expanded sections having an expanded pitch circle
diameter constituted by the plurality of heat-receiving pipes are
formed, and a heat input quantity per unit area of the
heat-receiving pipe is decreased in the portions near the
opening.
Inventors: |
Atarashiya; Kenji; (Tokyo,
JP) ; Horie; Shigenari; (Tokyo, JP) ; Mizuta;
Keiji; (Tokyo, JP) ; Maeda; Manabu; (Tokyo,
JP) ; Kobayashi; Kazuta; (Tokyo, JP) |
Assignee: |
MITSUBISI HEAVY INDUSTRIES,
LTD
TOKYO
JP
|
Family ID: |
44355338 |
Appl. No.: |
13/575982 |
Filed: |
January 28, 2011 |
PCT Filed: |
January 28, 2011 |
PCT NO: |
PCT/JP2011/051790 |
371 Date: |
July 30, 2012 |
Current U.S.
Class: |
126/663 ;
126/704 |
Current CPC
Class: |
F24S 80/40 20180501;
Y02E 10/44 20130101; F24S 60/00 20180501; F24S 10/748 20180501;
Y02E 10/40 20130101; F24S 20/20 20180501 |
Class at
Publication: |
126/663 ;
126/704 |
International
Class: |
F24J 2/24 20060101
F24J002/24; F24J 2/46 20060101 F24J002/46 |
Foreign Application Data
Date |
Code |
Application Number |
Feb 5, 2010 |
JP |
2010-024395 |
Claims
1. A solar heat receiver comprising: a casing having an opening on
which sunlight is incident; and a plurality of heat-receiving pipes
which are arranged in the casing in a circumferential direction of
the casing and through which a heat medium is circulated, wherein
the heat-receiving pipes are configured so that portions having
high heat flux on the opening side are extended to a radially outer
position of the casing, expanded sections constituted by the
plurality of heat-receiving pipes and having an expanded pitch
circle diameter are formed, and the diameter of the heat-receiving
pipe in the expanded section is greater than that of the
heat-receiving pipe in a portion other than the expanded
section.
2. (canceled)
3. The solar heat receiver according to claim 1, wherein a heat
transfer accelerator is equipped inside the heat-receiving pipe in
the expanded section.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a solar heat receiver for
increasing a temperature of a fluid medium that drives a turbine of
a solar heat power generator.
BACKGROUND ART
[0002] In recent years, in terms of prevention of global warming
and suppression of the use of fossil fuels, power generation using
clean energy such as natural energy having less harmful emissions
such as carbon dioxide and nitrogen oxides, and recycled energy
reusing the resources has received attention. The clean energy
exceeds a certain amount of electrical energy required by the whole
world. However, with regard to energy distribution of clean energy,
effective energy (energy that may be externally taken and utilized)
over a wide range is low. Due to this situation, since the power
generation using clean energy has low conversion efficiency to
power and high cost of power generation, such a power generation
has not been sufficiently propagated. Thus, as the power generation
type, power generation through solar thermal energy using power
generation techniques such as gas turbines, steam turbines, and a
gas turbine combined cycle (GTCC) is expected (for example, see
Patent Document 1).
[0003] And now, in the use of solar thermal energy, normally, the
light condensation and the heat collection are performed by a
combination of a light condenser using a mirror and a heat
receiver. As a combination method of the light condenser and the
heat receiver, generally, there are two kinds of methods including
a trough light condensation method and a tower light condensation
method.
[0004] The trough light condensation method is a method in which
solar light is reflected by a semi-cylindrical mirror (a trough),
light and heat are collected in a pipe passing through a center of
the cylinder, and the temperature of a thermal medium passing in
the pipe is increased. However, in the trough light condensation
method, the direction of the mirror is changed so as to track the
solar light, but since the control of the mirror is one-axis
control, it is difficult to expect a high temperature rise of the
thermal medium.
[0005] On the other hand, the tower light condensation method is a
method in which a light condensation heat receiver is arranged on a
tower section (a support section) erected from the ground, a
plurality of focusing reflected light control mirrors called a
heliostat (a solar light condensation system) are arranged so as to
surround the tower section, and the solar light reflected in the
heliostat is guided to the light condensation heat receiver to
perform light condensation and heat collection. Recently, in terms
of further improving the efficiency of the power generation cycle,
with regard to the thermal medium subjected to the heat exchange by
the light condensation heat receiver, development of a power
generator (a tower light condenser) of the tower light condensation
type capable of further raising the temperature has been actively
carried out.
PRIOR ART DOCUMENT
Patent Document
[0006] [Patent Document 1] Japanese Patent No. 2951297
DISCLOSURE OF THE INVENTION
Problems to be Solved by the Invention
[0007] However, in the heat receiver of the related art, the
following problem has occurred.
[0008] That is, in the heat exchanger in the tower light condenser
of the related art, the temperature of a fluid is raised by causing
the fluid to flow through a plurality of heat-receiving pipes
arranged on an inner surface of a cylindrical insulating container,
irradiating the surface of the heat-receiving pipe with sunlight,
and inputting heat. However, in this case, a difference in
temperature is increased between a front surface of the
heat-receiving pipe on which sunlight is directly incident and a
back surface facing a wall side. Particularly, when the mirrors are
arranged to be axially symmetrical, a heat load near an entrance of
the heat-receiving pipe is increased by the area effect of the
mirrors when the light is condensed and the temperature is
increased. Furthermore, the temperature difference is generated
between the front surface and the back surface of the
heat-receiving pipe due to cycles of day and night, influence of
clouds or a fluctuation in an irradiated amount of sunlight. As
such, there is a drawback that thermal fatigue is easily generated
particularly in the heat-receiving pipe near the entrance having a
high temperature and a large temperature difference, durability of
the heat-receiving pipe is required, and there is thus room for
improvement at this point.
[0009] The present invention has been achieved in view of the above
circumstances, and it is an object of the present invention to
provide a solar heat receiver that is able to improve a life
strength of the heat-receiving pipe by reducing a temperature
difference between front and back surfaces (a front portion and a
back portion in an incident direction of sunlight) of the
heat-receiving pipe.
Means for Solving the Problem
[0010] In order to achieve the object mentioned above, a solar heat
receiver according to the present invention includes a casing
having an opening on which sunlight is incident, and a plurality of
heat-receiving pipes which are arranged in the casing in a
circumferential direction of the casing and through which a heat
medium is circulated. The heat-receiving pipes are configured so
that portions having high heat flux on the opening side are
extended to a radially outer position of the casing and expanded
sections constituted by a plurality of heat-receiving pipes and
having an expanded pitch circle diameter are formed.
[0011] The solar heat receiver according to the present invention
is normally used in tower type solar heat power generation. The
solar heat receiver according to the present invention includes a
casing having an opening on which sunlight is incident, and a
plurality of heat-receiving pipes that are vertically arranged
inside the casing and raise the temperature of the heat medium
flowing therein by the irradiation of the sunlight. The plurality
of heat-receiving pipes are arranged so as to be spaced from each
other and to extend in one direction. Centers of the heat-receiving
pipes are arranged on the same circumference. The plurality of
heat-receiving pipes may be bent outward in a radial direction in a
portion near the opening of the casing. Thus, a circle passing
through the centers of the plurality of heat-receiving pipes is
configured so that a diameter in a region near the opening is
expanded compared to a diameter in a region separated from the
opening.
[0012] Herein, the pitch circle in the present invention is a
circle which intersects center axes of the plurality of
heat-receiving pipes through the centers of the heat-receiving
pipes. That is, the plurality of heat-receiving pipes are arranged
at a predetermined pitch (a space), and the centers thereof are
arranged on the circumference of the pitch circle.
[0013] In the present invention, by expanding the diameter of the
pitch circle in a portion of the heat-receiving pipe having high
heat flux, surface areas of the heat-receiving pipe and a heat
insulating material are increased in that portion, and thus it is
possible to reduce a heat input quantity per unit area to the
heat-receiving pipe. Moreover, the reduced amount of heat in the
heat-receiving pipe enters from an interval between the
heat-receiving pipes to the heat insulating material of the back
side, and heat is further diffused to the surrounding.
[0014] That is, sunlight, which is incident on the opening of the
casing and passes between the heat-receiving pipes, is incident on
a wall surface of the casing separated from the opening of the
casing behind the heat-receiving pipe. Moreover, the heat
insulating material or a heat absorption material forming the inner
wall surface of the casing is heated by sunlight passing between
the heat-receiving pipes. The heated heat insulating material or
the heat absorption material radiates heat, and heats the portion
of the back side of the heat-receiving pipe to which sunlight is
not directly irradiated.
[0015] According to the present invention, the interval between the
heat-receiving pipes in the portion of the heat-receiving pipe
having high heat flux near the opening of the casing is widened,
and the number of the heat-receiving pipes arranged per unit area
is reduced. Simultaneously, a distance between the heat-receiving
pipe and the opening of the casing, in which a diameter of luminous
flux of sunlight is minimized, is separated, and energy of sunlight
directly irradiated per unit area of the surface of the
heat-receiving pipe is reduced. Thus, in a region near the opening,
more sunlight than in the past passes between the heat-receiving
pipes, and energy of sunlight directly irradiated to the
heat-receiving pipe is reduced. For this reason, the heat flux of
the heat-receiving pipes may be reduced compared to the related art
in the region near the opening of the casing.
[0016] In this manner, the heat flux of the heat-receiving pipe
surface is reduced in a region in which the heat flux of the
heat-receiving pipe is easily increased near the opening of the
casing, and thus it is possible to reduce the temperature
difference between the front surface (a surface of the center axis
side of the casing) and the back surface (a surface of an inner
surface side of the casing) of the heat-receiving pipe. That is,
the temperature difference is reduced between a portion of the
front side of the heat-receiving pipe to which sunlight incident
from the opening of the casing is directly irradiated and a portion
of the back side of the heat-receiving pipe to which sunlight
incident from the opening of the casing is not directly irradiated.
Accordingly, life strength of the heat-receiving pipe may be
extended.
[0017] Furthermore, in the solar heat receiver according to the
present invention, the diameter of the heat-receiving pipe in the
expanded section may be greater than that of the heat-receiving
pipe in a portion other than the expanded section. That is, in a
region in which the diameter of the circle passing through the
centers of the heat-receiving pipes is expanded, the diameters of
each heat-receiving pipe may be expanded compared to the diameters
of each heat-receiving pipe in other regions.
[0018] In the present invention, by increasing the diameter of the
heat-receiving pipe in the region in which the diameter of the
circle passing through the center of the heat-receiving pipe is
expanded or the expanded section of the heat-receiving pipe, the
surface area of the outer circumferential surface of the
heat-receiving pipe is further expanded. Thus, it is possible to
increase the amount of heat exchange between the heat medium
flowing in the heat-receiving pipe and the heat-receiving pipe, and
thus the length of the heat-receiving pipe may be shortened.
Accordingly, it is possible to further reduce the temperature
difference between the portion (the front surface) of the front
side of the heat-receiving pipe to which sunlight is directly
incident and the portion (the back surface) of the back side to
which sunlight is not directly incident.
[0019] Furthermore, by expanding the diameter of the heat-receiving
pipe as mentioned above, the volume of the heat medium in the
heat-receiving pipe is increased. Thus, the heat medium in the
heat-receiving pipe is increased in heat capacity, the temperature
is not easily increased, and the temperature of the heat-receiving
pipe is not easily increased. Thus, it is possible to further
reduce the temperature difference between the front portion of the
heat-receiving pipe and the back portion thereof in the incident
direction of sunlight.
[0020] Furthermore, in the solar heat receiver according to the
present invention, a heat transfer accelerator may be equipped
inside the heat-receiving pipe in the expanded section. That is, in
a region in which the diameter of the circle passing through the
centers of the plurality of heat-receiving pipes is expanded, the
heat transfer accelerator having a thermal conductivity higher than
that of the heat-receiving pipe may be placed inside the
heat-receiving pipe. Furthermore, thermal conductivity of the heat
transfer accelerator may be higher than that of the heat
medium.
[0021] According to the present invention, it is possible to
increase the heat transfer coefficient inside the heat-receiving
pipe and more effectively transfer heat from the heat-receiving
pipe to the heat medium. Thus, since the amount of heat transfer
between the heat-receiving pipe and the heat medium may be
increased, length dimensions of the heat-receiving pipes may be
shortened, and thus the size of the heat receiver may be reduced.
Furthermore, when the diameter of the heat-receiving pipe is
expanded in the expanded section or the region in which the
diameter of the circle passing through the centers of the plurality
of heat-receiving pipes is expanded, the heat transfer accelerator
may be equipped inside the heat-receiving pipe without increasing
the pressure loss of the inside of the heat-receiving pipe compared
to other regions.
Effects of the Invention
[0022] According to the solar heat receiver of the present
invention, the temperature difference between the front portion and
the back portion of the heat-receiving pipe may be reduced, and
thus the life strength of the heat-receiving pipe may be
improved.
BRIEF DESCRIPTION OF THE DRAWINGS
[0023] FIG. 1 is a diagram showing a tower type solar light
condensation heat receiver according to a first embodiment of the
present invention.
[0024] FIG. 2 is a plan view showing an arrangement of heliostats
around a tower.
[0025] FIG. 3A is a transverse cross-sectional view showing a
schematic configuration of the tower top.
[0026] FIG. 3B is a longitudinal cross-sectional view showing a
schematic configuration of the tower top.
[0027] FIG. 4 is a perspective view showing a schematic
configuration of a heat receiver.
[0028] FIG. 5 is a perspective view of a heat-receiving pipe shown
in FIG. 4.
[0029] FIG. 6 is a cross-sectional view taken along line A-A shown
in FIG. 3B showing a configuration of an insulating material (a
radiation shield plate)
[0030] FIG. 7 is a perspective view that is seen from an arrow B of
FIG. 6.
[0031] FIG. 8 is a longitudinal cross-sectional view showing a
schematic configuration of the heat receiver.
[0032] FIG. 9 is a graph of solar heat incident intensity of the
heat-receiving pipe shown in FIG. 8.
[0033] FIG. 10 is a longitudinal cross-sectional view showing a
schematic configuration of a heat-receiving pipe according to a
second embodiment.
MODE(S) FOR CARRYING OUT THE INVENTION
[0034] Hereinafter, a solar heat receiver of an embodiment of the
present invention will be described with reference to the
accompanying drawings. The embodiment shows an aspect of the
present invention that is not limiting to the present invention,
but is able to be arbitrarily changed in the range of technical
ideas. Furthermore, in the drawings below, in order to better
understand each configuration, scales, numbers or the like are
different from those of an actual structure.
First Embodiment
[0035] A tower type solar power plant shown in FIG. 1 includes a
solar light heat receiver placed on a high tower, and mirrors
called heliostats which are placed on the ground around the solar
light heat receiver and are able to control reflected light. The
tower type solar power plant condenses sunlight on the solar light
heat receiver on the tower through the heliostats to generate
electricity.
[0036] As shown in FIG. 1, a heliostat field 101 is provided on the
ground G. A plurality of heliostats 102 for reflecting sunlight are
placed in the heliostat field 101. Furthermore, a tower type solar
light condensation heat receiver 100 which receives sunlight guided
by the heliostats 102 is provided in a central section of the
heliostat field 101. As shown in FIG. 2, the heliostats 102 are
placed 360.degree. around the entire circumference of the tower
type solar light condensation heat receiver 100.
[0037] The tower type solar light condensation heat receiver 100 is
constituted by a tower 110 erected on the ground G, an
accommodation chamber 120 over the tower 110, and a heat receiver
(a solar heat receiver) 10 provided in the accommodation chamber
120.
[0038] A plurality of reinforcing members 111 are provided in the
tower 110. The reinforcing members 111 are placed so as to
intersect the tower 110 in a height direction (a length direction)
and are provided at intervals (distances between the reinforcing
members adjacent to each other) P in the height direction of the
tower 110. The interval P is increased toward the top (a side
provided with the heat receiver 10) of the tower 10 in a range to
be included in an optical path through which reflected light of
sunlight is incident on the heat receiver 10 by the heliostat 102.
Accordingly, sunlight reflected by the heliostat 102 is condensed
in the heat receiver 10 on the tower 110 without being blocked by
the reinforcing members 111. In addition, the arrangement structure
of reinforcing members 111 may be, for example, a truss structure
in terms of ensuring rigidity.
[0039] As shown in FIG. 3A, the accommodation chamber 120 of the
top of the tower 110 has a circular plane shape.
[0040] As shown in FIG. 3B, the accommodation chamber 120 has two
accommodation chambers including an upper accommodation chamber 121
and a lower accommodation chamber 122. An opening 122c for
capturing sunlight is provided on a bottom of the lower
accommodation chamber 122. The plane shape of the opening 122c is a
circular shape. A diameter of the opening 122c is determined
depending on a spot diameter of sunlight. The diameter of the
opening 122c of the present embodiment is greater than or equal to
the spot diameter of sunlight. Herein, the spot diameter is a
diameter of a position at which the diameter of luminous flux of
sunlight, which is reflected by the heliostats 102 of the heliostat
field 101 and is incident on the opening 122c, is the smallest.
[0041] As shown in FIGS. 3A and 3B, the heat receiver 10 includes a
cylindrical casing 11 and a heat-receiving pipe 20. In addition,
the shape of the casing 11 is not limited to the cylindrical shape
and may be a conical shape, a polygonal column shape, a spherical
shape, an oval shape, or a combined shape of two or more of these.
The heat receiver 10 is provided in the lower accommodation chamber
122. Specifically, the heat receiver 10 is fixed to an upper wall
122a of the lower accommodation chamber 122 via a lifting tool 12,
and is suspended from the upper wall 122a in the lower
accommodation chamber 122. That is, the heat receiver 10 is placed
having a space between the inner walls in the position separated
from the inner wall of the lower accommodation chamber 122 so as
not to come into contact with the inner wall of the lower
accommodation chamber 122. A plurality of lifting tools 12 are
provided in the circumferential direction of the upper wall 122a
having a circular plane shape. The lifting tools have flexibility.
Furthermore, the lifting tools 12 pass through the casing 11. With
such a configuration, in case that the heat exchange is performed
between the heat-receiving pipe 20 and the heat medium flowing in
the heat-receiving pipe 20 on the inside of the heat receiver 10,
and even when the temperature of the casing 11 is increased (for
example, 900.degree. C. or more), the deformation due to the
thermal expansion of the casing 11 is allowed. Furthermore, an
opening 11b for capturing sunlight is provided on the lower surface
side (the bottom) of the casing 11. Like the opening 122c mentioned
above, the opening 11b is formed to have a circular plane shape.
The diameter of the opening 11b is determined depending on the spot
diameter of sunlight. The diameter of the opening 11b of the
present embodiment is greater than or equal to the spot diameter of
sunlight. Furthermore, the diameter of the opening 11b of the
casing 11 of the present embodiment is smaller than or equal to the
diameter of the opening 122c of the accommodation chamber 120.
[0042] In addition, in FIG. 3B, in order to better illustrate an
internal structure, the casing 11 is drawn in a cylindrical shape
of the same diameter in an axial direction. However, actually, as
shown in FIGS. 4 and 8, the casing 11 of the present embodiment has
an expanded section 11c in which a diameter of a lower portion
thereof is expanded so as to widen outward in the radial direction.
That is, the diameter of a lower part of the casing 11 near the
opening 11b is expanded compared to the diameter of an upper part
of the casing 11 separated from the opening 11b. A heat-receiving
pipe main body 23 extending in an axial direction (a vertical
direction) of the casing 11 along an inner wall surface of the
expanded section 11c is placed inside the expanded section 11c.
[0043] As shown in FIG. 3B, a gas turbine 30 which is operated
using fluid (the heat medium) heated by the heat receiver 10 as a
working fluid, and a generator 33 which extracts actuating energy
of the gas turbine 30 as electric power are placed inside the upper
accommodation chamber 121. The gas turbine 30 has a compressor 31
which sucks and compresses fluid (for example, atmosphere) serving
as the heat medium to generate a compressed fluid, and a turbine 32
which is operated using the fluid compressed by the compressor 31
and heated by the heat receiver 10 as the working fluid. Moreover,
kinetic energy generated by the rotation of the turbine 32 is
converted into electric energy by the generator 33 and is extracted
as electric power.
[0044] Devices such as a temperature sensor which detects heat
received by the heat receiver 10, an auxiliary drive device which
starts the gas turbine 30, a regenerative heat exchanger which
performs the heat exchange between the working fluid and the
exhaust of the turbine 32 before the working fluid is heated by the
heat receiver 10, an auxiliary combustor which performs auxiliary
combustion of the working fluid and causes the working fluid to
flow in the turbine 32, and a vibration damper which cancels the
vibration of the generator 33 may be placed inside the upper
accommodation chamber 121 as necessary. In this manner, an
installation area of the device may be reduced by integrally
placing the devices over the tower 110.
[0045] An opening 121b for capturing fluid (atmosphere) to be
supplied to the compressor 31 is provided on the side surface of
the upper accommodation chamber 121. In addition, the opening 121b
is used to discharge the exhaust from the turbine 32 to the outside
as necessary.
[0046] As shown in FIGS. 3A, 3B, 4 and 5, the heat-receiving pipe
20 has a lower header pipe 21, an upper header pipe 22, and a
heat-receiving pipe main body 23. The lower header pipe 21 has a
ring shape and is placed below the casing 11. Specifically, the
lower header pipe 21 is exposed to the outside of the casing 11 and
is placed near the lower wall 122b in the lower accommodation
chamber 122.
[0047] A plurality of heat-receiving pipe main bodies 23 are
provided inside the casing 11 in a vertical direction between the
upper header pipe 22 and the lower header pipe 21. The
heat-receiving pipe main bodies 23 are connected to the upper
header pipe 22 at one end thereof and are connected to the lower
header pipe 21 at the other end thereof. The heat receiving pipe
main bodies 23 raise the temperature of the working fluid (heat
medium) flowing therein from the lower header pipe 21 by the
irradiation of sunlight. The heated working fluid is discharged
from the heat-receiving pipe main body 23 to the upper header pipe
22. The heat-receiving pipe main bodies 23 are placed at
predetermined intervals (gaps) in the circumferential direction of
the upper header pipe 22 (the lower header pipe 21) (see FIGS. 6
and 7). The end portion of the heat receiving pipe main body 23
connected to the lower header pipe 21 is exposed to the outside of
the casing 11. Most of the part of the heat-receiving pipe main
bodies 23 is formed in a shape (a straight line shape) that extends
straight in the axial direction (a longitudinal direction) of the
casing 11. Bending stress due to self weight is not applied to the
portion of the heat-receiving pipe main bodies 23 formed in a
straight line.
[0048] Furthermore, the working fluid in the heat-receiving pipe
main body 23 flows from the lower header pipe 21 toward the upper
header pipe 23 in one direction.
[0049] The lower header pipe 21 is an annular pipe which is
inflected in a ring shape or a polygonal shape when viewed from
plane, and is disposed below the casing 11. Specifically, the lower
header pipe 21 is exposed to the outside of the casing 11 and is
placed near the lower wall 122b in the lower accommodation chamber
122. With the configuration mentioned above, the heat-receiving
pipe 20 is configured so that the upper header pipe 22 is fixed to
the upper wall 122a in the lower accommodation chamber 122 via the
lifting tool 12, all of which are suspended from the upper wall
122a.
[0050] An L-shaped inlet pipe 13 is connected to the lower header
pipe 21. A connection pipe 14 is connected between the inlet pipe
13 and the compressor 31. The connection pipe 14 is exposed to the
outside of the casing 11 and is placed along the inner wall of the
lower accommodation chamber 122. The compressed fluid generated by
the compressor 31 is supplied to the lower header pipe 21 via the
connection pipe 14 and the inlet pipe 13. The compressed fluid (the
heat medium) supplied to the lower header pipe 21 flows in the
plurality of heat-receiving pipe main bodies 23 and the upper
header pipe 22, and is heated by the heat-receiving pipe main body
23 and the upper header pipe 22 heated by thermal energy of
sunlight that is incident from the opening 11b.
[0051] As shown in FIGS. 4, 6 and 7, an insulating material (a heat
absorption material, a heat storage material or a radiation shield
plate) 15 absorbing the solar heat is provided on the inner wall
surface of the casing 11. The insulating material 15 is increased
in temperature by absorbing the heat, and radiates the heat to the
back surface (the portion of the back side on which sunlight is not
directly incident) of the heat-receiving pipe main body 23. In this
manner, the portion of the back side of the heat-receiving pipe 20
is heated by the thermal radiation of the insulating material 15
and the portion of the front side of the heat-receiving pipe 20 is
heated by sunlight, and thus, the entire heat-receiving pipe 20 in
the circumferential direction is heated. Furthermore, the
insulating material 15 sends radiation heat generated from the
heat-receiving pipe main body 23 back to the portion (the back
surface) of the back side of the heat-receiving pipe main body 23,
and stably heats the heat-receiving pipe main body 23. Furthermore,
the insulating material 15 reduces an amount of heat going outward
from the heat-receiving pipe main body 23 and the upper header pipe
22.
[0052] An outlet pipe 25 is connected to the upper header pipe 22
via a plurality of connecting pipes 24. The plurality of connecting
pipes 24 are configured so that one ends thereof are connected to
the upper header pipe 22, and the other ends thereof are connected
to the outlet pipe 25. The connecting pipes 24 are placed in an X
shape when viewed from the plane. The outlet pipe 25 is bent in the
upper accommodation chamber 121, and is formed in an L shape when
viewed from the plane shown in FIG. 3B. The end portion of the
outlet pipe 25 opposite to the side connected to the plurality of
connection pipes 24 is connected to the turbine 32. The compressed
fluid, which flows through the inside of the heat-receiving pipe
main body 23 and the upper header pipe 22 and is heated, is
supplied to the turbine 32 as the high-temperature high-pressure
working fluid via the connecting pipe 24 and the outlet pipe
25.
[0053] As shown in FIG. 8, the heat-receiving pipe main body 23
included in the heat-receiving pipe 20 of the heat receiver 10 is
configured so that the portion having high heat flux at the opening
11b side in the length direction extends to a position of the
outside of the casing 11 in the radial direction, and an expanded
section 20c is formed where a diameter D of the pitch circle formed
of the plurality of heat-receiving pipe main bodies 23 is expanded.
That is, the diameter D of the pitch circle of the expanded section
20c is greater than a diameter d of a pitch circle in a section 20d
other than the expanded section 20c. Herein, the pitch circle is a
circle that intersects a central axis of each heat-receiving pipe
main body 23 through the centers of the plurality of heat-receiving
pipe main bodies 23. That is, the plurality of heat-receiving pipe
main bodies 23 are arranged at predetermined pitches (gaps) in the
circumferential direction of the casing 11, and the centers thereof
are placed along the circumference of the pitch circle.
[0054] In other words, the plurality of heat-receiving pipe main
bodies 23 are placed so as to be separated from each other in the
circumferential direction of the casing 11 and to extend in the
vertical direction. The centers of the heat-receiving pipe main
bodies 23 are placed along the same circumference. The plurality of
heat-receiving pipe main bodies 23 are bent outward in the radial
direction of the casing 11 in the portion closer to the opening 11b
than the central section of the casing 11 in the vertical
direction. Accordingly, the expanded section 20c is provided in the
heat-receiving pipe main body 23 in a region near the opening 11b
of the casing 11. By providing the expanded section 20c in the
heat-receiving pipe main body 23, the circle passing through the
centers of the plurality of heat-receiving pipe main bodies 23 is
configured so that the diameter D in the region near the opening
11b is expanded compared to the diameter d in the region separated
from the opening 11b.
[0055] In addition, the heat-receiving pipe main body 23
corresponds to the heat-receiving pipe of the present
invention.
[0056] Furthermore, in FIG. 8, the insulating material 15 shown in
FIGS. 4, 6 and 7 is omitted.
[0057] Specifically, the expanded sections 20c of the
heat-receiving pipe main bodies 23 are placed along the inner
surface of the expanded section 11c of the casing 11 mentioned
above at predetermined intervals and form a substantially
trapezoidal shape when viewed from the side, and the lower ends
thereof are projected outward from the casing 11.
[0058] FIG. 9 is a graph showing an effect of the expanded section
20c of the heat-receiving pipe main body 23 included in the
heat-receiving pipe 20, a vertical axis thereof indicates the
length (a distance from the opening 11b) X of the heat-receiving
pipe main body 23, and a horizontal axis thereof indicates a heat
input quantity (solar heat incident intensity) to the
heat-receiving pipe main body 23. In FIG. 9, a dotted line is a
result of a case in which the expanded section 20c is not provided
in the heat-receiving pipe main body 23, and a solid line is a
result of a case in which the expanded section 20c is provided. As
shown in FIG. 8, by providing the expanded section 20c in a high
temperature section K of the heat-receiving pipe main body 23 near
the opening 11b, the incident solar strength to the heat-receiving
pipe main body 23 is lowered as shown in FIG. 9.
[0059] In the solar heat receiver according to the first embodiment
mentioned above, the diameter D of the pitch circle is expanded in
the portion having high heat flux (the high temperature section K)
of the heat-receiving pipe main bodies 23 included in the
heat-receiving pipe 20. Accordingly, the surface area of the outer
circumferential surface of the heat-receiving pipe 20 in that
portion is expanded. In other words, the interval between the
heat-receiving pipe main bodies 23 in the high temperature section
K of the heat-receiving pipe main bodies 23 near the opening 11b of
the casing 11 is widened, and the number of the heat-receiving pipe
main bodies 23 to which sunlight is irradiated per unit area in the
region is reduced. At the same time, the distance between the
heat-receiving pipe main bodies 23 and the opening 11b of the
casing 11, in which the diameter of luminous flux of sunlight is
minimal, is separated, and energy of directly irradiated sunlight
per unit area of the surface of the heat-receiving pipe main bodies
23 is reduced. Accordingly, in the region near the opening 11b,
more sunlight than in the related art passes between the
heat-receiving pipe main bodies 23, and it is possible to reduce
the heat input quantity per unit area to the heat-receiving pipe
main bodies 23 (see FIG. 9). Moreover, the reduced amount of heat
in the heat-receiving pipe 20 including the heat-receiving pipe
main bodies 23 enters the insulating material 15 (see FIGS. 6 and
7) provided behind (the back side of) the heat-receiving pipe main
bodies 23 through the gap between the heat-receiving pipe main
bodies 23, and the heat is further diffused to the surroundings
thereof.
[0060] In this manner, the heat flux of the surface of the
heat-receiving pipe main bodies 23 is reduced, it is possible to
reduce the temperature difference between the portion (the front
surface) 20a (the surface facing the central axis of the casing 11)
of the front side of the heat-receiving pipe main bodies 23 and the
portion (the back surface) 20b (the surface facing the inner
surface of the casing 11) of the back side thereof, and thus the
life strength of the heat-receiving pipe 20 may be extended.
[0061] Moreover, the fluctuation of a gas temperature of the
heat-receiving pipe outlet is suppressed, the set gas temperature
of the outlet side may be stabilized, and thus the operation of the
turbine may be stabilized.
[0062] Next, another embodiment of the solar heat receiver of the
present invention will be described based on the accompanying
drawings. In the present embodiment, the same or similar members
and portions as those of the first embodiment mentioned above are
denoted by the same reference numerals, the descriptions thereof
will be omitted, and configurations different from those of the
first embodiment will be described.
Second Embodiment
[0063] As shown in FIG. 10, a heat receiver (a solar heat receiver)
10A according to a second embodiment is configured so that a pipe
diameter of an expanded section 20e in the heat-receiving pipe main
bodies 23 included in the heat-receiving pipe 20 is greater than
that of a portion other than the expanded section 20e. That is, in
a region in which the diameter of the circle passing through the
center of each heat-receiving pipe main body 23 is expanded, the
diameter of each heat-receiving pipe main body 23 is expanded
compared to the diameter of each heat-receiving pipe main body 23
in other regions.
[0064] In this manner, by increasing the diameter of the expanded
section 20e of the heat-receiving pipe main bodies 23 included in
the heat-receiving pipe 20, the surface area of the outer
circumferential surface of the heat-receiving pipe 20 is further
increased, and thus the heat input quantity per unit area may be
further reduced. Furthermore, by enlarging the diameter of the
heat-receiving pipe main bodies 23, the volume of the compressed
fluid in the heat-receiving pipe main bodies 23 is increased.
Accordingly, the compressed fluid in the heat-receiving pipe main
bodies 23 is increased in heat capacity, the temperature does not
rise easily, and the temperature of the heat-receiving pipe main
bodies 23 does not rise easily either. Thus, it is possible to
further reduce the temperature difference between the portion (the
front surface) of the front side of the heat-receiving pipe main
bodies 23 and the portion (the back surface) of the back side
thereof to the incident direction of sunlight.
[0065] In addition, the expanded section 20e of the heat-receiving
pipe main bodies 23 may be equipped with a heat transfer
accelerator 20h. That is, the heat transfer accelerator 20h having
thermal conductivity higher than that of the heat-receiving pipe
main bodies 23 may be placed inside the heat-receiving pipe main
bodies 23 in the region in which the diameter D of the circle
passing through the centers of the plurality of heat-receiving pipe
main bodies 23 is expanded. Furthermore, the thermal conductivity
of the heat transfer accelerator 20h may be higher than that of the
compressed fluid flowing in the heat-receiving pipe main bodies
23.
[0066] According to the present embodiment, by increasing the
diameter of the expanded section 20e of the heat-receiving pipe
main bodies 23 included in the heat-receiving pipe 20, the heat
transfer accelerator 20h may be equipped inside the heat-receiving
pipe main bodies 23 without increasing the pressure loss. At the
same time, the heat transfer coefficient inside of the
heat-receiving pipe main bodies 23 may be increased. Accordingly,
since an amount of heat exchange between the heat-receiving pipe
main bodies 23 and the compressed fluid may be increased, the
length dimension of the heat-receiving pipe main bodies 23 may be
shortened, and thus the heat receiver 10A may be downsized.
[0067] For example, the pipe diameter of the heat-receiving pipe
main bodies 23 is 1.3 times that of the expanded section 20e, the
expanded section 20e is equipped with the heat transfer accelerator
20h, and it is therefore possible to expand the amount of heat
exchange by about 1.6 to 2.4 times compared to an original pipe
diameter.
[0068] Although the embodiments of the solar heat receiver
according to the present invention have been described, the present
invention is not limited to the embodiments mentioned above.
Additions, omissions, substitutions, and other variations may be
made to the present invention without departing from the spirit and
scope of the present invention. The present invention is not
limited by the above description, but only by the appended
claims.
[0069] For example, in the present embodiment, although the shape
of the expanded section 20c of the heat-receiving pipe 20 is
substantially a trapezoidal shape when viewed from the side, the
shape is not limited thereto. For example, in the region in which
the portion having the high heat flux (the high temperature section
K) near the opening 11b is included, a tapered shape which
gradually spreads radially outward from the casing 11 toward the
bottom or in an umbrella shape may be adopted.
[0070] Furthermore, the pipe diameter dimension of the expanded
section 20e of the heat-receiving pipe main bodies 23 having the
large diameter in the second embodiment may be arbitrarily set, and
may be determined depending on the conditions such as the presence
or the absence of the heat transfer accelerator as mentioned
above.
[0071] In addition, the components of the embodiments mentioned
above may be suitably replaced with well-known components, and the
embodiments mentioned above may be suitably combined with each
other.
INDUSTRIAL APPLICABILITY
[0072] A solar light heat receiver includes a casing having an
opening on which sunlight is incident, and a plurality of
heat-receiving pipes that are vertically arranged inside the casing
and raise the temperature of a heat medium flowing therein by the
irradiation of the sunlight. The plurality of heat-receiving pipes
are arranged so as to be spaced from each other and to extend in
one direction. Centers of the respective heat-receiving pipes are
arranged on the same circumference. The plurality of heat-receiving
pipes are bent outward in the radial direction in a portion near
the opening of the casing. Thus, a circle passing through the
centers of the plurality of heat-receiving pipes is configured so
that a diameter in a region near the opening is expanded compared
to a diameter in a region separated from the opening.
DESCRIPTION OF REFERENCE NUMERALS AND SIGNS
[0073] 10, 10A: heat receiver (solar heat receiver) [0074] 11:
casing [0075] 11b: opening [0076] 11c: expanded section [0077] 15:
insulating material [0078] 20: heat-receiving pipe [0079] 20a:
front surface [0080] 20b: back surface [0081] 20c, 20e: expanded
section [0082] 20h: heat transfer accelerator [0083] 23:
heat-receiving pipe main body [0084] D, d: pitch circle diameter
[0085] K: high temperature section
* * * * *