Pulse detonation combustor heat exchanger   

Abstract: The present application provides a pulse detonation combustor heat exchanger. The pulse detonation combustor heat exchanger may include one or more pulse detonation combustors creating combustion gases therein, one or more inner pathways positioned about the pulse detonation combustors, and a working medium flowing in the inner pathways so as to exchange heat with the combustion gases in the pulse detonation combustors.

TECHNICAL FIELD

The present application relates generally to pulse detonation combustors and systems and more particularly relates to the use of pulse detonation combustors for highly efficient heat exchangers such as boilers and the like.

BACKGROUND OF THE INVENTION

Known pulse detonation combustors generally operate with a detonation process having a pressure rise as compared to conventional engines operating with a constant pressure deflagration. Specifically, air and fuel are mixed within a pulse detonation combustion chamber and ignited to produce a combustion pressure wave. The combustion pressure wave transitions into a detonation wave followed by combustion gases that produce heat and thrust. As such, pulse detonation combustors have the potential to operate at higher thermodynamic efficiencies than generally may be achieved with conventional deflagration based engines.

Recent developments in pulse detonation combustors have focused on practical applications such as generating additional thrust/propulsion for aircraft engines and improving the overall performance in ground based power generation systems. Pulse detonation combustors also have been used as a means for highly efficient boiler cleaning and the like.

Industrial boilers operate by using a heat source to create steam from water or another type of working medium. The steam may be used to drive a turbine or another type of a load. The heat source may be a combustor that burns a fuel-air mixture therein. Heat may be transferred to the working medium from the combustor via a heat exchanger. The efficiency of the boiler or other type of heat exchanger is based in part on the heat transfer rate to the working medium. In general, heat transfer rates for boilers and similar devices tend to be much higher for turbulent flows as compared to laminar flows.

There is thus a desire to adapt the highly efficient pulse detonation combustors for use in heat exchangers such as boilers and the like. The use of such a pulse detonation combustor should provide a higher heat transfer rate, with less fuel consumption, and while being more compact in size as compared to conventional boilers and the like.

SUMMARY

The present application thus provides a pulse detonation combustor heat exchanger. The pulse detonation combustor heat exchanger may include one or more pulse detonation combustors creating combustion gases therein, one or more inner pathways positioned about the pulse detonation combustors, and a working medium flowing in the inner pathways so as to exchange heat with the combustion gases in the pulse detonation combustors.

The present application further provides a pulse detonation combustor boiler. The pulse detonation boiler may include one or more pulse detonation combustors creating combustion gases therein, a number of boiler tubes positioned about the pulse detonation combustors, and a working medium flowing in the boiler tubes so as to exchange heat with the combustion gases in the pulse detonation combustors.

The present application further provides a pulse detonation combustor heat exchanger. The pulse detonation combustor heat exchanger may include an outer chamber, one or more pulse detonation combustors positioned within the outer chamber creating combustion gases therein, one or more inner chambers positioned within the outer chamber, and a working medium flowing in the inner chambers so as to exchange heat with the combustion gases in the pulse detonation combustors.

These and other features and advantages of the present application will become apparent to one of ordinary skill in the art upon review of the following detailed description when taken in conjunction with the several drawings and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic view of a known pulse detonation combustor.

FIG. 2 is a schematic view of a pulse detonation combustor heat exchanger as may be described herein.

FIG. 3 is a side plan view of the pulse detonation combustor heat exchanger of FIG. 2.

FIG. 4 is a schematic view of a pulse detonation combustor boiler as may be described herein.

FIG. 5 is a side plan view of the pulse detonation combustor boiler of 4.

DETAILED DESCRIPTION

As used herein, the term “pulse detonation combustor” refers to a device or a system that produces both a pressure rise and a velocity increase from the detonation or quasi-detonation of a fuel and an oxidizer. The pulse detonation combustor may be operated in a repeating mode to produce multiple detonations or quasi-detonations within the device. A “detonation” may be a supersonic combustion in which a shock wave is coupled to a combustion zone. The shock may be sustained by the energy release from the combustion zone so as to result in combustion products at a higher pressure than the combustion reactants. A “quasi-detonation” may be a supersonic turbulent combustion process that produces a pressure rise and a velocity increase higher than the pressure rise and the velocity increase produced by a sub-sonic deflagration wave, i.e., detonation and fast flames. For simplicity, the terms “detonation” or “detonation wave” as used herein will include both detonations and quasi-detonations.

Exemplary pulse detonation combustors, some of which will be discussed in further detail below, include an ignition device for igniting a combustion of a fuel/oxidizer mixture and a detonation chamber in which pressure wave fronts initiated by the combustion coalesce to produce a detonation wave. Each detonation or quasi-detonation may be initiated either by an external ignition source, such as a spark discharge, laser pulse, heat source, or plasma igniter, or by gas dynamic processes such as shock focusing, auto-ignition, or an existing detonation wave from another source (cross-fire ignition). The detonation chamber geometry may allow the pressure increase behind the detonation wave to drive the detonation wave and also to blow the combustion products themselves out an exhaust of the pulse detonation combustor. Other components and other configurations may be used herein.

Various combustion chamber geometries may support detonation formation, including round chambers, tubes, resonating cavities, reflection regions, and annular chambers, Such combustion chamber designs may be of constant or varying cross-section, both in area and shape. Exemplary combustion chambers include cylindrical tubes and tubes having polygonal cross-sections, such as, for example, hexagonal tubes. As used herein, “downstream” refers to a direction of flow of at least one of the fuel or the oxidizer.

Referring now to the drawings, in which like numbers refer to like elements throughout the several views, FIG. 1 shows a generalized example of a pulse detonation combustor 10 as may be described and used herein. The pulse detonation combustor 10 may extend from an air inlet 15 and one or more fuel inlets 20 at a head end to an exit nozzle 25 at an opposed downstream end. A combustion tube 30 may extend from the head end to the exit nozzle 25 at the downstream end. The combustion tube 30 defines a combustion zone 35 therein. Other components and other configurations may be used herein for detonation and/or quasi-detonation.

The air inlet 15 may be connected to a source of pressurized air such as a. compressor. The pressurized air may be used to flu and purge the combustion zone 35 and also may serve as an oxidizer for the combustion of the fuel. The air inlet 15 may be in communication with a center body 40. The center body 40 may extend towards the combustion zone 35. The center body 40 may have any size, shape, or configuration. Likewise, the fuel inlet 20 may be connected to a supply fuel that may be burned within the combustion zone 35. The fuel may be injected into the combustion zone 35 so as to mix with the airflow.

An ignition device 45 may be positioned downstream of the air inlet 15 and the fuel inlet 20. The ignition device 45 may be connected to a. controller so as to operate the ignition device 45 at desired times and sequences as well as providing feedbacks signals to monitor overall operations. As described above, any type of ignition device 45 may be used herein. The fuel and the air may be ignited by the ignition device 45 into a combustion flow so as to produce the resultant detonation waves. Other components and other configurations may be used herein. Any type of pulse detonation combustor 10 may be used herein.

FIGS. 2 and 3 show a pulse detonation combustor heat exchanger 100 as may be described herein. The pulse detonation combustor heat exchanger 100 may include a number of pulse detonation combustors 110 positioned therein. As described above, each pulse detonation combustor 110 includes a combustion tube 120 that defines a combustion zone 130 therein. Each pulse detonation combustor 110 also includes an air inlet 140, a fuel inlet 150, and an igniter 160, Other components and other configurations may be used herein. The air and the fuel are ignited by the igniter 160 to create a. flow of combustion gases 170 within the combustion zone 130 of each combustion tube 120.

The pulse detonation combustion heat exchanger 100 includes an outer chamber 180. The pulse detonation combustors 110 are positioned within the outer chamber 180, The pulse detonation combustor heat exchanger 100 also includes one or more inner pathways 190 extending through the outer chamber 180. The one or more inner pathways 190 may be one or more chambers 195, a series of tubes, and similar types of transport structures, The inner pathway 190 may extend from a cold inlet 200 to a hot outlet 210. The inner pathway 190 may be positioned about a. pair of headers 220, A preheater 230 also may be used about the cold inlet 200. The inner pathway 190 may be positioned about the combustion tubes 120 of the pulse detonation combustors 110. The positioning may be in a cross-flow orientation, a co-flow orientation, a counter-flow orientation, or any desired flow orientation. A working medium 240 may flow through the inner pathway 190. The working medium 240 may be any type of gas or liquid that absorbs heat therein.

In use, the pulse detonation combustors 110 generate the hot combustion gases 170 within the combustion zone 130 of each combustion tube 120. Likewise, the working medium 240 enters the outer chamber 180 via the cold inlet 200. The working medium 240 exchanges the heat with and is warmed by the combustion gases 170. The now hot working medium 240 then passes through the hot outlet 210 for useful work in a turbine or other type of harvesting device. The combustion gases 170 also may be vented for use downstream for preheaters, super heaters, economizers, and the like. The inner pathway 190 also may be used as a blockage device for heat transfer therewith.

The generation of the combustion gases 170 thus increases the heat transfer rate from the combustion tubes 120 to the working medium 240. The detonation conditions produce shock waves that scour away the protective layer of inactive gas or particles on the tube walls so as to increase the rate of heat transfer. The use of the pulse detonation combustors 1.10 also should reduce fouling of the inner pathway 190. The pulse detonation combustors 110 also have less unburned fuel so as to reduce overall. emissions.

FIGS. 4 and 5 show an alternative embodiment of the pulse detonation combustor heat exchanger 100. In this example, a pulse detonation combustor boiler 250 is shown. As above, the pulse detonation combustor boiler 250 includes a number of the pulse detonation combustors 110. Each pulse detonation combustor 110 includes the combustion tube 120 so as to define the combustion zone 130, Each pulse detonation combustor 110 also includes the air inlet 140, the fuel inlet 150, and the igniter 160 so as to produce the flow of combustion gases 170.

The pulse detonation combustor boiler 250 also includes a number of boiler tubes 260 in communication with a pair of headers 270. An economizer 280 or other type of heat exchanger may be positioned downstream of the boiler tubes 260. A number of the combustion tubes 120 may be positioned in one direction with a further number of the combustion tubes 120 positioned in an opposing direction. The boiler tubes 260 may be positioned in a cross-flow orientation. Any type of flow orientation may be used herein.

In use, the pulse detonation combustors 110 create the flow of hot combustion gases 170 within the combustion zone 130 of each combustion tube 120 about the boiler tubes 260 and the economizer 280 to downstream. Heat thus is exchanged with the cold working medium 240 from the economizer 280 through the connection tubes to the bottom water header 270 and then through the boiler tubes 260 to the top steam header 270. The now hot working medium 240 or steam then may flow from the top header 270 to the next station for useful work via a turbine or other type of harvesting device. The combustion gases 170 likewise may be vented for downstream use after the economizer 280. Other components and other configurations may be used herein.

It should be apparent that the foregoing relates only to certain embodiments of the present application and that numerous changes and modifications may be made herein by one of ordinary skill in the art without departing from the general spirit and scope of the invention as defined by the following claims and the equivalents thereof.