U.S. patent application number 15/035835 was filed with the patent office on 2016-10-06 for heat exchanger.
The applicant listed for this patent is MITSUBISHI HITACHI POWER SYSTEMS, LTD.. Invention is credited to Masashi KITADA, Toshifumi KUDO, Takahiro OKIMOTO, Naoki SUGANUMA, Tetsuya YAMADA.
Application Number | 20160290742 15/035835 |
Document ID | / |
Family ID | 53478081 |
Filed Date | 2016-10-06 |
United States Patent
Application |
20160290742 |
Kind Code |
A1 |
OKIMOTO; Takahiro ; et
al. |
October 6, 2016 |
HEAT EXCHANGER
Abstract
An object is to provide a heat exchanger including a
resonance-prevention baffle plate disposed between a plurality of
heat transfer tubes, the resonance-prevention baffle plate being
obtainable and mountable readily and at lower cost. A heat
exchanger 10 disposed in a flow passage of combustion gas of a
boiler or the like includes: a plurality of heat transfer tubes 14
disposed in parallel and spaced from one another, an axial
direction of each heat transfer tube intersecting with the
combustion gas g, inside a duct wall 12 forming the flow passage of
the combustion gas g; and a resonance-prevention baffle 16 having a
plate shape and disposed along the combustion gas g and between the
heat transfer tubes 14, the resonance-prevention baffle including a
metal foil sheet 18.
Inventors: |
OKIMOTO; Takahiro; (Tokyo,
JP) ; SUGANUMA; Naoki; (Tokyo, JP) ; KUDO;
Toshifumi; (Tokyo, JP) ; YAMADA; Tetsuya;
(Tokyo, JP) ; KITADA; Masashi; (Tokyo,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
MITSUBISHI HITACHI POWER SYSTEMS, LTD. |
Yokohama-shi, Kanagawa |
|
JP |
|
|
Family ID: |
53478081 |
Appl. No.: |
15/035835 |
Filed: |
September 10, 2014 |
PCT Filed: |
September 10, 2014 |
PCT NO: |
PCT/JP2014/073986 |
371 Date: |
May 11, 2016 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
F28F 9/22 20130101; F22B
37/10 20130101; F28F 2265/30 20130101; F28F 2009/224 20130101; F28D
7/1615 20130101; F28F 9/00 20130101; F22B 37/20 20130101 |
International
Class: |
F28F 9/22 20060101
F28F009/22; F22B 37/20 20060101 F22B037/20; F28D 7/16 20060101
F28D007/16 |
Foreign Application Data
Date |
Code |
Application Number |
Dec 27, 2013 |
JP |
2013-271370 |
Claims
1. A heat exchanger, comprising: a plurality of heat transfer tubes
disposed in parallel and spaced from one another, an axial
direction of each heat transfer tube intersecting with a flow
passage of a heat-exchange target fluid; a resonance-prevention
baffle having a plate shape and disposed along a flow direction of
the heat-exchange target fluid and between the plurality of heat
transfer tubes, the resonance-prevention baffle comprising a metal
foil sheet; and a rigid frame member fixed to an outer peripheral
portion of the metal foil sheet.
2. (canceled)
3. The heat exchanger according to claim 1, wherein the
resonance-prevention baffle is fixed to at least a part of the
plurality of heat transfer tubes by a fixing member.
4. The heat exchanger according to claim 3, wherein the fixing
member comprises a U-shape bolt disposed so as to surround the heat
transfer tube and screwed to the resonance-prevention baffle at
opposite ends.
5. The heat exchanger according to claim 1, wherein the plurality
of heat transfer tubes is disposed linearly along the flow
direction of the heat-exchange target fluid, and wherein the
resonance-prevention baffle is formed into a flat plate shape and
disposed along the flow direction of the heat-exchange target
fluid.
Description
TECHNICAL FIELD
[0001] The present invention relates to a heat exchanger disposed
on a boiler, for instance, the heat exchanger including a
resonance-prevention baffle disposed between a group of heat
transfer tubes.
BACKGROUND ART
[0002] A boiler or the like has a heat exchanger disposed in a duct
housing forming a flow passage of combustion gas, the heat
exchanger including a super-heater, a re-heater, and an economizer,
for example. Such a heat exchanger includes a plurality of heat
transfer tubes disposed inside a duct housing, and a medium such as
water flowing through the heat transfer tubes is heated by
combustion gas to transform into steam. The steam is sent to a
steam turbine to be used for power generation. The plurality of
heat transfer tubes is disposed so that the axial direction of each
heat transfer tube intersects with the flow passage of combustion
gas, and spaced in parallel from one another.
[0003] The heat transfer tubes are disposed in a direction
orthogonal to combustion gas g inside a duct wall forming the flow
passage of combustion gas. FIG. 4 is a diagram of an example of a
duct wall 100 forming a flow passage of combustion gas g and heat
transfer tubes 102 disposed in a grid pattern in the flow passage
of the combustion gas g inside the duct wall 100. FIG. 5 is a
diagram of an example of heat transfer tubes 102 disposed in a
staggered pattern.
[0004] As depicted in FIG. 6, in response to combustion gas g
flowing through a group of such heat transfer tubes, Karman
vortices e are generated periodically downstream of a heat transfer
tube 102. A generation frequency fk (Hz) of Karman vortices e can
be expressed by the following expression:
Fk=StV/D (1)
, where St is a Strouhal number, V is a minimum gap flow rate (flow
rate between heat transfer tubes), and D is an outer diameter of a
heat transfer tube.
[0005] Meanwhile, a duct wall orthogonal to a flow of combustion
gas and orthogonal to the axial direction of heat transfer tubes
has a unique vibrational mode determined by a physical property of
the combustion gas g. The unique vibrational frequency fn (Hz) is
expressed by the following expression:
Fn=nc/2L (2)
, where n is 1, 2, 3, . . . , and c is sonic speed (depending on
the temperature of the combustion gas g), and L is a distance
between duct walls 100.
[0006] FIG. 7 shows a vibrational mode in the primary mode of n=1,
where v represents a velocity component and p represents a pressure
component. If the generation frequency fk matches one of unique
vibration frequencies fn (n=1, 2, 3, . . . ), a resonance state is
created, and excessive noise called tube singing is generated.
[0007] Tube singing is normally addressed and prevented by avoiding
resonance by providing a resonance-prevention baffle of a plate
shape along a flow of combustion gas between a group of heat
transfer tubes to increase the unique vibrational frequency fn.
[0008] FIG. 8 is a diagram of an example with such a
resonance-prevention baffle plate 104. In FIG. 8, a flow passage of
combustion gas g is formed by a duct wall 100. Heat transfer tubes
102 are disposed in a direction orthogonal to a direction of flow
of combustion gas g in the flow passage of the combustion gas g.
The resonance-prevention baffle plate 104 is disposed between the
heat transfer tubes 102 and along a direction of flow of the
combustion gas g.
[0009] Patent Documents 1 and 2 disclose a heat exchanger
including: a plurality of heat transfer tubes disposed in parallel
in a flow passage of heat-exchange target gas; and a
resonance-prevention baffle plate disposed along a direction of
flow of a heat-exchange target fluid between the heat transfer
tubes.
CITATION LIST
Patent Literature
[0010] Patent Document 1: JPS59-012293A [0011] Patent Document 2:
JPH05-141891A
SUMMARY
Problems to be Solved
[0012] A typical resonance-prevention baffle plate has a heavy
weight, and a significant amount of work hours and cost may be
required to fix a resonance-prevention baffle plate with a heavy
weight in a flow passage of a heat-exchange target fluid.
[0013] In view of the above problem of conventional techniques, an
object of the present invention is to make configuration and
installation work of a resonance-prevention baffle plate simple and
less expensive.
Solution to the Problems
[0014] To achieve the above object, a heat exchanger according to
an embodiment of the present invention comprises: a plurality of
heat transfer tubes disposed in parallel and spaced from one
another, an axial direction of each heat transfer tube intersecting
with a flow passage of a heat-exchange target fluid; and a
resonance-prevention baffle having a plate shape and disposed along
a flow direction of the heat-exchange target fluid and between the
plurality of heat transfer tubes, the resonance-prevention baffle
comprising a metal foil sheet.
[0015] A resonance-prevention baffle plate has a function to
increase a unique vibrational frequency fn generated inside a duct
wall forming the flow passage of the heat-exchange target fluid and
to differentiate the unique vibrational frequency fn from a
frequency fk generated by Karman vortices e produced downstream of
the heat transfer tubes.
[0016] The unique vibrational frequency fn can be increased by
partitioning the flow passage of the heat-exchange target fluid and
forming a boundary where the particle velocity of the heat-exchange
target fluid is zero. Thus, the above function can be achieved even
by a thin partition wall such as a metal foil sheet.
[0017] According to an embodiment of the present invention, the
resonance-prevention baffle includes a metal foil sheet and thus
can be reduced in weight. Thus, it is possible to reduce material
cost and to make works required to mount and replace the
resonance-prevention baffle plate simple and less expensive.
[0018] An embodiment of the present invention further comprises a
rigid frame member fixed to an outer peripheral portion of the
metal foil sheet. A metal foil sheet may deform in response to a
heat-exchange target fluid. Thus, with the rigid frame member being
fixed to the metal foil sheet, it is possible to apply rigidity to
the metal foil sheet. Accordingly, it is possible to prevent
deformation of the metal foil sheet and to maintain rigidity such
that the metal foil sheet does not deform in response to a flow of
a heat-exchange target fluid, without increasing too much
weight.
[0019] In an embodiment of the present invention, the
resonance-prevention baffle is fixed to at least a part of the
plurality of heat transfer tubes by a fixing member.
[0020] As described above, since the resonance-prevention baffle of
the present invention can be reduced in weight, it is possible to
mount the resonance-prevention baffle to the heat transfer tube
readily by using a fixing member with less strength. Furthermore,
since the resonance-prevention baffle has less weight, it is
sufficient if the resonance-prevention baffle is fixed to only a
part of the heat exchanger tubes, which reduces the load of
mounting work.
[0021] In an embodiment of the present invention, the fixing member
comprises a U-shape bolt disposed so as to surround the heat
transfer tube and screwed to the resonance-prevention baffle at
opposite ends. With the U-shape bolt having the above
configuration, it is possible to further facilitate mounting
work.
[0022] In an embodiment of the present invention, the plurality of
heat transfer tubes is disposed linearly along the flow direction
of the heat-exchange target fluid, and the resonance-prevention
baffle is formed into a flat plate shape and disposed along the
flow direction of the heat-exchange target fluid.
[0023] Thus, it possible to readily insert the resonance-prevention
baffle plate between the heat transfer tubes, which are ready-made
members, and to set the resonance-prevention baffle plate in a
predetermined position. Thus, it is possible to mount or replace
the resonance-prevention baffle without removing the heat transfer
tubes, which are ready-made members. Further, it is no longer
necessary to install the heat transfer tubes after mounting the
resonance-prevention baffle, which makes it possible to reduce a
considerable amount of man hours for mounting and replacing.
Advantageous Effects
[0024] According to an embodiment of the present invention, the
resonance-prevention baffle includes a metal foil sheet and thus
has less weight, which makes it possible to make mounting work of
the resonance-prevention baffle simple and less expensive.
BRIEF DESCRIPTION OF DRAWINGS
[0025] FIG. 1 is a front cross-sectional view of a heat exchanger
according to the first embodiment of the present invention.
[0026] FIG. 2 is a pre-assembly perspective view of a
resonance-prevention baffle plate of the heat exchanger.
[0027] FIG. 3 is a post-assembly perspective view of the
resonance-prevention baffle plate.
[0028] FIG. 4 is a front cross-sectional view of a general
grid-pattern arrangement of heat transfer tubes.
[0029] FIG. 5 is a front cross-sectional view of a general
staggered arrangement of heat transfer tubes.
[0030] FIG. 6 is a diagram for describing Karman vortices e
generated downstream of a heat transfer tube.
[0031] FIG. 7 is a diagram for describing unique vibration
generated inside a duct wall of a heat exchanger.
[0032] FIG. 8 is a front cross-sectional view of a typical heat
exchanger.
DETAILED DESCRIPTION
[0033] Embodiments of the present invention will now be described
in detail with reference to the accompanying drawings. It should be
noted that, unless otherwise particularly specified, the sizes,
materials, shapes, and relative arrangement or the like of
constituent components described in these embodiments are not
intended to limit the scope of this invention.
[0034] A heat exchanger according to the first embodiment of the
present invention will be described with reference to FIGS. 1 and
3. The present embodiment is an example in which a heat exchanger
10 according to the first embodiment of the present invention is
applied to a heat exchanger such as a super-heater, a re-heater,
and an economizer, or to a waste-heat recovery boiler, for
instance, disposed on a steam boiler incorporated into a thermal
power generation plant.
[0035] In FIG. 1, a flow passage of combustion gas g is formed by a
duct housing constituting the heat exchanger 10 of the present
embodiment. A plurality of heat transfer tubes 14 is disposed
inside a duct wall 12 constituting the duct housing. The duct
housing has, for instance, a quadrilateral or circular cross
section.
[0036] The heat transfer tubes 14 are disposed in parallel and
spaced from one another, and the axial direction of each heat
transfer tube 14 is orthogonal to the combustion gas g. The heat
transfer tubes 14 are arranged in a grid pattern. Specifically, the
heat transfer tubes 14 are arranged in lines extending linearly in
a direction of flow of the combustion gas g, and also in a
direction orthogonal to the direction of flow of the combustion gas
g.
[0037] The combustion gas g exchanges heat with a medium such as
water flowing inside each heat transfer tube 14 while flowing
between the heat transfer tubes 14, and the medium such as water is
heated by the combustion gas g to transform into steam. The steam
is sent to a steam turbine to be used for power generation.
[0038] Two resonance-prevention baffles 16 are inserted between the
heat transfer tubes 14 and fixed to the heat transfer tubes 14. The
resonance-prevention baffle 16 includes a metal foil sheet 18
having a flat surface and is disposed along the direction of flow
of the combustion gas g. As described above, the
resonance-prevention baffle 16 is disposed to partition the flow
passage of the combustion gas g, thereby forming a boundary in a
flow rate of the combustion gas g. Accordingly, it is possible to
increase a resonance frequency generated inside the duct wall
12.
[0039] As described above, the unique vibrational frequency fn of
the unique vibrational mode formed inside the duct wall 12 by the
flow of the combustion gas g is differentiated from the generation
frequency fk of Karman vortices e generated behind each heat
transfer tube 14, which makes it possible to prevent generation of
excessive noise.
[0040] As illustrated in FIGS. 2 and 3, the resonance-prevention
baffle plate 16 includes a metal foil sheet 18 of a quadrilateral
shape made of high-temperature stainless steel (SUH 409L) having a
thickness of 10 to 1000 .mu.m, for example, 20 .mu.m. It should be
noted that the material of the metal foil sheet 18 is selected on
the basis of the temperature of a heat-exchange target fluid, and
the thickness of the metal foil sheet 18 is selected on the basis
of the hardness, viscosity, or the like of the selected
material.
[0041] Further, the length of a side of the metal foil sheet used
in the present invention is determined on the basis of the length
of a boiler casing and the number of stages of a heat exchanger,
and is 20 m (duct width).times.2 m (number of stages of a heat
exchanger), for instance.
[0042] The metal foil sheet 18 deforms in response to a flow of
combustion gas. Thus, an outer peripheral portion of the metal foil
sheet 18 is nipped by frame members 20, 20 having rigidity from
both sides. The two frame members 20 are fastened by bolts 22 and
nuts 24 at where needed. It should be noted that head portions of
the bolts 22 and the nuts 24 should be buried into the frame
members 20, 20 as much as possible so as not to generate a
turbulence in the flow of combustion gas.
[0043] As illustrated in FIG. 1, the resonance-prevention baffle
plate 16 is fixed to the heat transfer tubes 14 by using a U-shape
bolt 26. Specifically, the U-shape bolt 26 has male screws formed
on opposite ends, and is disposed so as to surround the heat
transfer tube 14, and the male screws of the opposite ends of the
U-shape bolt 26 are engaged with female screw holes formed on the
resonance-prevention baffle plate 16. Alternatively, the opposite
ends may be inserted through holes formed on the
resonance-prevention baffle plate 16, and the male screws may be
engaged with nuts 28 to fix the resonance-prevention baffle plate
16 to the heat transfer tube 14.
[0044] It should be noted that a position of mounting using the
U-shape bolt 26 may be a position required to achieve a necessary
fixing strength of the resonance-prevention baffle 16.
[0045] According to the present embodiment, the
resonance-prevention baffle plate 16 includes the metal foil sheet
18 and thus can be reduced in weight. Thus, it is possible to
reduce material cost and to make works required to mount and
replace the resonance-prevention baffle plate 16 simple and less
expensive.
[0046] Further, with the outer peripheral portion of the metal foil
sheet 18 fastened from both sides by the two frame members 20, 20
with rigidity, it is possible to maintain rigidity so as not to
deform in response to a flow of combustion gas without increasing
too much weight.
[0047] Further, since the resonance-prevention baffle plate 16 can
be reduced in weight, it is possible to mount the
resonance-prevention baffle plate 16 to the heat transfer tube 14
readily by using a fixing member with less strength. Thus, it is
possible to fix the resonance-prevention baffle plate 16 firmly by
using a less expensive fixing member.
[0048] Furthermore, since the resonance-prevention baffle plate 16
has less weight, it is sufficient if the resonance-prevention
baffle plate 16 is fixed to only a part of the heat transfer tubes
14, which reduces the load of mounting work.
[0049] Still further, since the U-shape bolt 26 is used as a fixing
unit of the resonance-prevention baffle plate 16, it is possible to
simplify the mounting work even further.
[0050] Further, the heat transfer tubes 14 are disposed in a grid
pattern and the resonance-prevention baffle plate 16 is formed into
a flat plate shape, which makes it possible to readily insert the
resonance-prevention baffle plate 16 between the heat transfer
tubes 14, which are ready-made members, and to set the
resonance-prevention baffle plate 16 in a predetermined
position.
[0051] Thus, it is possible to mount or replace the
resonance-prevention baffle plate 16 without removing the heat
transfer tubes 14, which are ready-made members, or without
mounting the heat transfer tubes 14 after mounting the
resonance-prevention baffle plate 16.
[0052] In the above described embodiment, the present invention is
applied to a heat exchanger including heat transfer tubes disposed
in a grid pattern. However, the present invention can be also
applied to a heat exchanger including heat transfer tubes disposed
in a staggered or zig-zag pattern by modifying a method to fix a
metal foil sheet.
INDUSTRIAL APPLICABILITY
[0053] According to the present invention, for a heat exchanger
including a plurality of heat transfer tubes disposed in parallel
and a resonance-prevention baffle plate disposed between the heat
transfer tubes, it is possible to make configuration and
installation work of a resonance-prevention baffle plate simple and
less expensive.
DESCRIPTION OF REFERENCE NUMERALS
[0054] 10 Heat exchanger [0055] 12, 100 Duct wall [0056] 14, 102
Heat transfer tube [0057] 16, 104 Resonance-prevention baffle plate
[0058] 18 Metal foil sheet [0059] 20 Frame member [0060] 22 Bolt
[0061] 24, 28 Nut [0062] 26 U-shape bolt [0063] e Karman vortex
[0064] g Combustion gas
* * * * *