Heat exchange – With adjustor for heat – or exchange material – flow – Branched flow
Reexamination Certificate
2000-04-10
2001-10-16
Flanigan, Allen (Department: 3746)
Heat exchange
With adjustor for heat, or exchange material, flow
Branched flow
C165SDIG001
Reexamination Certificate
active
06302191
ABSTRACT:
FIELD OF THE INVENTION
This invention relates generally to heat exchangers having internal bypass arrangements which may be actuated to control the bypass of hot gas around a heat exchanger array and to direct gas flow into a bypass circuit. It particularly relates to beat exchangers associated with gas turbines and gas/diesel engines for extracting heat from their exhaust gases.
BACKGROUND OF THE INVENTION
Heat exchangers of the type used to recover heat from gas turbine or gas/diesel engine exhaust gas are commonly designed with a bypass circuit situated external to the heat exchanger array and its casing, with the exhaust gas flow to the heat exchanger array circuit and the bypass circuit controlled by one or two flap valves or the like, such valves being known as dampers. Arrangements are known in which a single damper controls the flow through both circuits. Alternatively, two damper arrangements are known, in which one damper controls the flow through the heat exchanger array circuit and the other damper controls the flow through the bypass circuit. Both types tend to be heavy, bulky and complicated and when such dampers have been continuously modulated for continuously variable flow control reliability problems have been experienced. For example. with two damper arrangements, damage to engines has been caused by excessive back-pressure due to both dampers being closed at the same time, instead of one circuit always being open.
BRIEF DESCRIPTION OF THE INVENTION
According to the present invention, a heat exchange unit for exhaust gas heat recovery has heat exchange duct means, bypass duct means, heat exchange array means situated within the heat exchange duct means, and a variable position sleeve valve arrangement adapted to cause variable amounts of exhaust gas to flow through the bypass duct means instead of the heat exchange duct means, the heat exchange array means surrounding the variable position sleeve valve arrangement and the latter defining the bypass duct means and an inner wall of the heat exchange duct means, the variable position sleeve valve arrangement including sleeve means moveable axially of both duct means thereby simultaneously to control flow of exhaust gas through the heat exchange duct means and the bypass duct means.
Preferably, the sleeve means is adapted to be axially continuously moveable between two extreme positions with respect to inlet means for the heat exchange duct means and outlet means for the bypass duct means, whereby at one extreme position the inlet means for the heat exchange duct means is open and the sleeve means obturates outlet means for the bypass duct means and at the other extreme position the sleeve means obturates the inlet means for the heat exchange duct means and the outlet means for the bypass duct means is open.
One benefit of the current invention is that the modulating sleeve valve mechanism is an integral part of the heat exchange unit, rather than a separate piece of equipment, and is much simpler in its design than the prior art damper, making modulation more reliable. A further benefit is the intrinsically safe nature of the sleeve valve arrangement, wherein it is not possible to close off both gas flow paths at the same time, thereby protecting the upstream equipment from overpressure damage. A further benefit is that the current invention is lighter and requires less space than the prior art arrangements, which is of considerable benefit in offshore applications.
Furthermore in the known designs it is usual for there to be a separate sound attenuator installed in the gas circuit either upstream or down stream of the heat exchanger unit. In the current invention it is possible to favorably design the unit with sound attenuation linings on one or both sides of the sleeve means to damp sound in the bypass duct and/or the heat exchanger duct. It is possible also to provide the bypass duct with a flow splitter situated in the center of the sleeve means, the flow splitter also having a sound attenuating lining on its surface confronting the sleeve means. These measures would be intended to eliminate the requirement for a separate attenuation device.
Further features and advantages of the invention will be apparent from the following description and the claims.
REFERENCES:
patent: 3392777 (1968-07-01), Edgemond, Jr. et al.
patent: 3991821 (1976-11-01), Cook et al.
patent: 4371054 (1983-02-01), Wirt
patent: 4498524 (1985-02-01), Jacobsen
patent: 5396760 (1995-03-01), Hines
patent: 554803 (1957-02-01), None
patent: 42 07 677 A1 (1993-09-01), None
patent: 43 10 538 A1 (1994-10-01), None
patent: 0 357 907 A1 (1989-07-01), None
patent: 415986 (1934-09-01), None
Jamieson Richard
Wickham Mark Frederick
Alstom UK Limited
Flanigan Allen
Kirschstein et al.
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