Patent Application
20080022684
Referring now to
In the illustrated embodiment, segmented heat exchanger system 1 may include a plurality of individual heat exchangers, such as, for example, first heat exchanger 10, second heat exchanger 20, and third heat exchanger 30. Although the illustrated example depicts three individual heat exchangers, one skilled in the art will readily recognize that segmented heat exchanger system 1 may include a greater or lesser number of individual heat exchangers, and that individual heat exchangers 10, 20, 30 may be of any suitable configuration and/or type known in the art. For exemplary purposes only, first heat exchanger 10 may include a parallel flow preheater, second heat exchanger 20 may include a counter flow vaporizer, and third heat exchanger 30 may include a parallel flow superheater.
With continuing reference to
Next, in order to maximize exhaust heat utilization while managing surface temperatures of the heat exchangers, the working fluid 40 leaving first heat exchanger 10 at exit 41 may be piped directly to second heat exchanger 20, such as, for example, a vaporizer. Exhaust gases 50, however, may bypass the second heat exchanger 20 and be ducted from the first heat exchanger 10 directly to the third heat exchanger 30, which may include, for example, a superheater, to heat working fluid 40 entering the third heat exchanger 30 from the second heat exchanger 20. Both exhaust gases 50 and working fluid 40 may also travel through third heat exchanger 30 in a parallel flow arrangement, as discussed above in connection with first heat exchanger 10.
Exhaust gases 50 may next be ducted from third heat exchanger 30 to the second heat exchanger 20, to heat working fluid 40 entering second heat exchanger 20 from first heat exchanger 10. As shown in
While it is contemplated that additional individual heat exchangers may be utilized with the segmented heat exchanger system 1, the illustrated embodiment provides for exhaust gases 50 leaving second heat exchanger 20 via stack 53 to escape segmented heat exchanger system 1 into, for example, the atmosphere. Similarly, working fluid 40 may be piped out of segmented heat exchanger system 1 to, for example, a high pressure turbine (not shown).
The segmented heat exchanger system 1, first, second, and third heat exchangers 10, 20, 30, and the method of recapturing residual heat energy in exhaust gases 50 to heat a working fluid 40 of the present disclosure are generally applicable to any system that uses a heated working fluid and consequently produces a hot exhaust fluid. Such systems may include, but are not limited to, power producing plants, fuel systems, coal burning systems, turbines, and engines.
In addition to addressing working fluid degradation, as mentioned above and will be discussed further below, segmented heat exchanger system 1 may improve overall efficiency of any system utilizing a heated working fluid. Systems that utilize a heated working fluid generally require burning a fuel, such as, for example, coal, to produce the heat necessary to heat the working fluid. Segmented heat exchanger system 1 may provide for the recapture of a portion of any wasted exhaust heat, to aid in the heating of the working fluid, thereby increasing the overall efficiency of the burned fuel and the system. In addition, utilizing residual exhaust heat may result in a reduction of fuel necessary to adequately heat the working fluid, harmful agents released into the atmosphere, and operating costs.
As eluded to above, the segmented heat exchanger system 1 and the method of recapturing residual heat energy in exhaust gases 50 to heat a working fluid 40 of the present disclosure may find particular applicability in relation to systems utilizing an organic Rankine cycle in which exceedingly high surface temperatures of heat exchangers may result in working fluid degradation. By utilizing a segmented heat exchanger arrangement in which individual heat exchangers are designed for specific purposes such as, for example, preheating, vaporizing, and superheating, by operating the first and third heat exchangers 10, 30 in a parallel flow arrangement, by operating the second heat exchanger 20 in a counter flow arrangement, and by channeling the exhaust gases 50 and working fluid 40 as discussed above, the segmented heat exchanger system 1 of the present disclosure may provide for maximum heat transfer while maintaining heat exchanger surface temperatures below the fluid degradation temperature of the working fluid, thereby reducing working fluid breakdown.
It will be apparent to those skilled in the art that various modifications and variations can be made to the segmented heat exchanger system 1 of the present disclosure without departing from the scope of the disclosure. In addition, other embodiments will be apparent to those skilled in the art from the consideration of the specification and practice of the system disclosed herein. It is intended that the specification and examples be considered as exemplary only, with a true scope of the disclosure being indicated by the following claims and their equivalents.
This invention was made with government support under the terms of DE-FC26-01CH11079 awarded by the Department of Energy. The government may have certain rights in this invention.
