U.S. patent number 3,877,519 [Application Number 05/383,705] was granted by the patent office on 1975-04-15 for pressurized strongback regenerator.
This patent grant is currently assigned to General Electric Company. Invention is credited to William M. Knox, James G. Miller, Salvatore S. Tramuta.
United States Patent |
3,877,519 |
Tramuta , et al. |
April 15, 1975 |
Pressurized strongback regenerator
Abstract
A gas turbine regenerator including at least one regenerator
section having a central air plenum with heat exchanger tube banks
disposed on either side. Each tube bank includes pressurized air
chambers at each end for preventing warping or bowing at each tube
bank end thus obviating the use of relatively thick structural ribs
at each end section. The pressurized air chambers are relatively
thin thereby improving the thermal mass ratio between the end
sections and the tube banks. Each air chamber is pressurized during
regenerator operation by bleeding pressurized air from the central
air plenum.
Inventors: |
Tramuta; Salvatore S.
(Schenectady, NY), Miller; James G. (Schenectady, NY),
Knox; William M. (Amsterdam, NY) |
Assignee: |
General Electric Company
(Schenectady, NY)
|
Family
ID: |
23514329 |
Appl.
No.: |
05/383,705 |
Filed: |
July 30, 1973 |
Current U.S.
Class: |
165/166;
159/28.6; 60/39.511 |
Current CPC
Class: |
F02C
7/10 (20130101); F28D 9/00 (20130101); F28F
2265/26 (20130101) |
Current International
Class: |
F28D
9/00 (20060101); F02C 7/08 (20060101); F02C
7/10 (20060101); F28f 003/00 () |
Field of
Search: |
;165/166 ;159/28P |
References Cited
[Referenced By]
U.S. Patent Documents
Primary Examiner: Myhre; Charles J.
Assistant Examiner: Streule, Jr.; Theophil W.
Attorney, Agent or Firm: Berrier, Jr.; Erwin F.
Government Interests
BACKGROUND OF THE INVENTION
This invention was made under contract with the U.S. Government
under Contract 0-35510 with the U.S. Maritime Administration of the
Department of Commerce. The U.S. Government is licensed in
accordance with the terms of the aforesaid contract and has
reserved the rights set forth in Section 1 (f) and 1 (g) of the
Oct. 10, 1963 Presidential Statement of Government Patent Policy.
Claims
What is claimed is:
1. In a heat exchanger of the type having a stack of heat exchanger
plates arranged in close, spaced relationship so as to define
alternating first and second fluid flow passages therebetween, and
means for directing high pressure fluid into and from said first
passages, the improvement comprising:
means for holding the heat exchanger plates of each said stack
together, said means comprising a pressure chamber at each end of
said stack of plates, each said pressure chamber including a
generally flat bottom plate and an arcuate outer wall, each said
pressure chamber disposed with its flat bottom plate abutting and
covering the first heat exchanger plate at its end of the stack,
means connecting said pressure chambers to each other, and means
for pressurizing said pressure chambers, whereby the pressure
forces generated by said high pressure fluid in said first passages
and which tend to urge the plates forming each first passage to
separate are countered by the pressure forces in said pressure
chamber which act against the flat bottom plate of said
chamber.
2. The heat exchanger of claim 1 further characterized in that said
arcuate outer wall includes a semi-circular main body portion and
partial spherical end portions.
3. The heat exchanger of claim 1 further characterized in that the
ends of said pressure chambers extend beyond the width of said heat
exchanger plates and have spaced, generally parallel, reinforcing
ribs secured thereto.
4. The heat exchanger of claim 1 further characterized in that said
means for pressurizing said pressure chambers comprise means for
communicating each of said pressure chambers with said high
pressure fluid directing means.
5. A heat exchanger comprising:
at least one heat exchanger tube bank, each said tube bank
comprising a plurality of closely spaced, generally parallel plates
defining alternating first and second heat transfer flow passages
therebetween; inlet plenum means for delivery of a flow of
pressurized fluid to said first heat transfer flow passages; outlet
plenum means for receiving pressurized fluid flow from said first
heat transfer flow passages; means for holding said plates together
against the force generated by said high pressure fluid, said
holding means comprising a pressure vessel at each end of said tube
bank means, each said vessel including an arcuate outer wall joined
to a generally flat bottom plate, said bottom plate lying against
and covering the first tube bank plate at its end of the tube bank;
means connecting said pressure vessels together; and means for
pressurizing said pressure vessel.
6. The heat exchanger of claim 5 further characterized in that
there are two tube banks and said inlet and outlet plenum means are
disposed intermediate said tube bank means.
7. The heat exchanger of claim 5 further characterized in that said
means for pressurizing said pressure vessel comprise means for
communicating each said pressure vessel with said inlet plenum
means.
8. The heat exchanger of claim 5 further characterized in that the
ends of each said pressure chamber extend beyond the ends of its
adjacent tube bank plate, said arcuate outer wall including a
semi-circular main body portion and partial spherical end portion,
with the portions of said pressure vessel bottom plate which extend
beyond the tube bank plate having reinforcing ribs secured thereto.
Description
This invention relates, in general, to heat exchangers; and, in
particular, this invention relates to gas turbine regenerators. A
regenerator is used in a gas turbine power plant to heat compressor
discharge air prior to its entry into the combustion chambers
thereby reducing the amount of fuel necessary to bring the
combustion gases to the required operating temperatures. Heat is
transferred to the compressor discharge air from hot turbine
exhaust gases which pass through the regenerator in heat transfer
relation with the compressor discharge air. The regenerator
includes alternating stacked air and gas channels of the plate-fin
type to effect the heat transfer.
Prior art gas turbine regenerators have included box-like
structures having plate-fin tube banks with the entire regenerator
banded together by tie straps interconnecting massive structural
end frames. Compressor discharge air, at relatively high pressure
(about 130 psia) may tend to warp or bow the end frame structure.
In the prior art this was prevented by using a plurality of
relatively thick structural ribs incorporated into the massive end
frame. This construction presented an undesirable thermal mismatch
because of relatively low thermal mass of the tube banks as
contrasted with the relatively large thermal mass of the end
frames. This thermal mass mismatch results in unequal rates of
expansion between the tube banks and end frames creating
undesirable stresses.
SUMMARY OF THE INVENTION
The present invention greatly decreases the prior art end frame
mass and consequent thermal mismatch by replacing the structural
ribs in the end frame by pressurized air chambers comprising
relatively thin shells at each end of the tube bank. The
pressurized air chambers are pressure-tight and supplied with air
pressure derived from a bleed connected to an air plenum between
the tube banks. In the preferred embodiment compressor discharge
air enters an air inlet plenum, passes through a pair of tube
banks, one disposed on each side of the air plenum and then exits
from an air outlet plenum which is in communication with each
pressurized air chamber by means of a tube interconnected between
the air outlet plenum and each pressurized air chamber.
It is therefore one object of the present invention to minimize the
thermal mass mismatch between the tube banks and end frame of a
regenerator.
It is still another object of the present invention to provide
pressurized end supports for a regenerator which will always be
pressurized during regenerator operation.
These and other objects and advantages will become apparent from
the following description of one embodiment of the invention and
the novel features will be particularly pointed out hereinafter in
the claims.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a diagram of a gas turbine regenerative cycle with
representative air and gas temperatures shown at selected
points.
FIG. 2 is a partially cutaway perspective view of a gas turbine
regenerator according to the present invention.
FIG. 3 is a partially cutaway and exploded perspective view of a
gas turbine regenerator section according to the present
invention.
DETAILED DESCRIPTION OF THE INVENTION
Referring to FIG. 1, a gas turbine is coupled at one end to an air
compressor and at the other end to a load. Air is drawn into the
compressor at atmospheric pressure 14.7 psia and is discharged from
the compressor at approximately 130 psia and thereafter channeled
to the regenerator. Relatively low pressure (14.7 psia), high
temperature, gas turbine exhaust gases are channeled to the
regenerator from the turbine. Thereafter, the exhaust gases and the
compressor discharge air pass in a heat exchange relation through
the regenerator. The exhaust gases are directed to the exhaust
stack while the compressor discharge air is channeled, at elevated
temperature, to a combustion chamber.
A gas turbine regenerator 11 is shown in FIG. 2 with broad arrows
indicating respective exhaust gas flows and compressor discharge
air flows. The regenerator includes a minimal outer frame 13
including flanged portions for connecting the regenerator into a
gas turbine exhaust duct (not shown). The air and gas flow is shown
to be substantially counterflow, for example, but other flow
arrangements, which would be apparent to those having skill in the
art, are considered to be within the true spirit and scope of the
present invention. The regenerator may include any number of
sections 15, two of which are shown as the preferred
embodiment.
Referring to FIG. 3, a single regenerator section is shown having a
length L and a width W. A central air plenum 21 extends the length
of the section including an air inlet manifold 23 and an air outlet
manifold 25. Heat transfer tube banks 27 are positioned on either
side of the central air plenum and include alternating gas channels
29 and air channels 31. The air plenum is divided into an air inlet
plenum 35 and an air outlet plenum 37 which are interconnected by
the air channels 31 as shown, a portion of the air flowing through
the air inlet plenum is distributed to each air channel and then to
the air outlet plenum. The air channels are relatively narrow and
the air pressure relatively high.
The low pressure, high temperature exhaust gas flow is counter to
the high pressure air flow. The relatively wide gas channels 29
include corrugated passageways and are sealed along the width of
the heat transfer tube banks. The ends of the gas channels are open
for gas flow therethrough. The air channels 31 are sealed at all
edges except for portions aligned with the inlet and outlet air
plenum on the sides adjacent the air plenum.
At each end of each heat transfer tube bank there is an air chamber
41 comprising a semicylindrical body portion and quarter-spherical
end caps 43. The semicylindrical body portion and quarter-spherical
end caps include a flat side 42 adjacent the tube bank. The end
caps at each end of each air chamber reduce the force due to air
pressure and at the ends, the flat side 42 overhangs beyond the
tube bank width, the nonpressurized outer side being reinforced by
ribs to prevent warping of the air pressure chamber about the ends
of the tube banks due to air pressure in the air chamber.
At the air outlet plenum, tubes 45 interconnect each air chamber 41
with the air outlet plenum so that each air chamber is pressurized
during regenerator operation. Obviously air may be secured from a
source independent of regenerator operation such as a pressurized
air tank. Pressurized air is preferably bled from the hotter air
outlet plenum in order to further equalize thermal growth in the
end sections with thermal growth in the tube banks.
Each tube bank may include tie straps 51 which are connected to the
tube banks along the length L and also which may be connected at
each end to opposite air chambers, thereby substantially enveloping
each tube bank. The tie straps 51 may extend along the outside
surfaces of the tube banks, as shown; and, also the tie straps may
extend along the inside surface of the tube bank (not shown) and
therefore be disposed between each tube bank and the air plenum.
Separate tie straps may be used to tie together the tube bank and
to tie each end air chamber to the tube bank and still fall within
the scope of the present invention.
The operation of the invention may be described as follows. As the
regenerator operates, the high pressure compressor discharge air
exerts a force which would tend to push apart the air channels
within the regenerator tube banks. This force is restrained by the
tie straps 51 which envelop the tube bank. However, at each end of
the tube bank the air pressure exerts a force which tends to bow
outwardly or warp the end sections of the regenerator. In the prior
art this force was countered by thick structural ribs which
reinforced the end plates of the regenerator. This construction
increased the thermal mass of the end sections which gave rise to
undesirable stressing. The present invention obviates the use of
structural ribs by utilizing pressurized air chambers which prevent
end warping while decreasing thermal mass by using thin pressurized
shells. Moreover, bleeding pressurized air from the regenerator
itself insures a supply of pressurized air as long as the
regenerator is operative and, moreover, the use of the air outlet
plenum air further contributes to equal temperature rise in both
the tube bundles and end sections.
While there is shown what is considered to be, at present, the
preferred embodiment of the invention, it is, of course, understood
that various other modifications may be made therein and it is
intended to cover in the appended claims all such modifications as
fall within the true spirit and scope of the invention.
* * * * *