Patent Description:
The presently-disclosed invention relates generally to nuclear reactors and, more specifically, to devices for desuperheating exhaust steam from nuclear thermal propulsion engines.

The concept of utilizing nuclear thermal propulsion (NTP) to propel spacecraft during space travel is known. In developing the technology related to propelling spacecraft in this manner, it is necessary to be able to test the NTP engines while minimizing the potential release of fission products into the environment. As such, rocket exhaust capture systems (RECS) have been proposed to receive the exhaust from a corresponding NTP engine during active testing. One such RECS <NUM> is shown in <FIG>. The NTP engine <NUM> being tested is disposed within a shielded engine containment <NUM>, with the hydrogen exhaust plume being received in a duct <NUM> after passing through a water-cooled diffuser <NUM> that transitions the exhaust plume flow from supersonic to subsonic in order to allow stable burning with injected liquid oxygen (LO<NUM>). By-products include steam, excess O<NUM> and potentially a small fraction of noble gasses (e.g., xenon, krypton, etc.).

In order to collect the exhaust and associated by-products, the exhaust plume is passed through water cooled ducts <NUM> prior to entering a first heat exchanger <NUM>. Heat is dissipated from the steam/O<NUM>/noble gas mixture in the heat exchanger <NUM> in order to lower the mixture temperature and condense the steam. The condensate is collected in a water tank <NUM> along with any radioactive particulates that may be entrained in the flow. A filter <NUM> is used to clear the drainage prior to release. A second heat exchanger <NUM> is also used to cool the residual gasses for storage in a LOX demar <NUM>. The inability to properly cool the exhaust plume prior to entering the first heat exchanger <NUM> can lead to reduced efficiencies and potential issues within the first heat exchanger <NUM> and water tank <NUM>. <CIT> discloses a reactor steam circulator. <CIT> discloses an ice making apparatus.

There at least remains a need, therefore, for improved devices for desuperheating the exhaust plumes of NTP engines during testing operations.

The invention is defined by the features of independent claim <NUM>. One example of the present invention provides a desuperheating spray chamber for use in a rocket exhaust recovery system for a nuclear thermal propulsion rocket, including a substantially-cylindrical outer tank with an upper end including an entrance port and two exhaust ports disposed thereon, a substantially-cylindrical shroud extending downwardly from an inner surface of the upper end of the tank, wherein the shroud is concentric to the entrance port about a longitudinal center axis of the outer tank, an annular inner spray ring that is both disposed within and concentric to the shroud about the longitudinal center axis, and an annular outer spray ring that is disposed between a side wall of the outer tank and the shroud, the annular outer ring being concentric to the shroud about the longitudinal center axis.

One embodiment of the present invention provides a desuperheating spray chamber for use in a rocket exhaust recovery system for a nuclear thermal propulsion rocket, having a substantially-cylindrical outer tank with an upper end including an entrance port and at least one exhaust port disposed thereon, a substantially-cylindrical shroud extending downwardly from an inner surface of the upper end of the tank, an inner spray ring that is disposed within the shroud about a longitudinal center axis of the outer tank; and an outer spray ring that is disposed between a side wall of the outer tank and the shroud.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention.

The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not, all embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure.

The invention now will be described more fully hereinafter with reference to the accompanying drawings, in which some, but not all, embodiments of the invention are shown. Indeed, this invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will satisfy applicable legal requirements. As used in the specification, and in the appended claims, the singular forms "a", "an", "the", include plural referents unless the context clearly dictates otherwise.

Referring now to the figures, the present invention is directed to desuperheating spray chambers and is figured to cool high temperature, high velocity exhaust steam from a nuclear thermal propulsion (NTP) engine as part of a rocket exhaust collection system (RECS). As shown in <FIG>, a desuperheating spray chamber <NUM> in accordance with the present invention includes a substantially-cylindrical outer tank <NUM> including an entrance port <NUM> and two exhaust ports <NUM> on its upper end <NUM>, a substantially-cylindrical inner shroud <NUM> extending downwardly from its upper end <NUM>, a manway <NUM> extending radially-outwardly from its side wall, a drain assembly <NUM> extending downwardly from its bottom end <NUM>, an inner and outer spray rings <NUM> and <NUM>, respectively, disposed within the upper end of the tank. The entrance port <NUM> is configured to receive a rocket exhaust plume <NUM> (<FIG>) and is centrally located in the upper end <NUM> of the outer tank <NUM> to help ensure symmetry of the effects of the exhaust plume on the spray chamber <NUM>. In a like manner, the exhaust ports <NUM> are disposed on opposite sides of the entrance port <NUM> so that the saturated steam exiting the spray chamber <NUM> also affects the spray chamber <NUM> in a symmetrical fashion. The manway <NUM> on the side wall of the tank <NUM> facilitates both maintenance operations as well as inspections of the interior of the spray chamber <NUM>. The drain assembly <NUM> allows excess condensate that may accumulate in the spray chamber <NUM> during exhaust recovery operations to be drained to a corresponding water tank (not shown) for storage and later processing. A plurality of instrumentation ports <NUM> are also provided in the side wall of the tank <NUM> to facilitate monitoring operating parameters such as, but not limited to, temperature, pressure, etc..

Referring additionally to <FIG>, the shroud <NUM> is mounted to the inner surface of the upper end <NUM> of the tank <NUM> and is concentric to the entrance port <NUM> about a longitudinal center axis <NUM> of the tank <NUM>. The inner shroud <NUM> extends only partially into the outer tank <NUM> and helps maintain the temperature of the upper portion of the tank's side wall within a desirable range as the rocket exhaust plume enters the spray chamber <NUM> by way of entrance port <NUM>. As well, the shroud <NUM> so helps to direct the exhaust plume downwardly within the tank <NUM> to help insure proper mixing with the spray from the inner and outer spray rings <NUM> and <NUM>. Preferably, the inner shroud <NUM> includes a plurality of apertures <NUM> along its upper edge to help maintain the upper components of spray chamber <NUM> within the desired temperature range. The apertures <NUM> allow some of the cooler steam that is about to exit the spray chamber <NUM> to be entrained into the interior of the shroud <NUM> by the exhaust plume <NUM> (<FIG>), thereby helping to reduce the temperature of the exhaust plume <NUM> and the upper portion of the shroud <NUM> that is exposed to the highest temperatures. As best seen in <FIG>, the inner spray ring <NUM> is disposed within an upper portion of the inner shroud <NUM> and is concentric about the longitudinal center axis <NUM> of the spray chamber <NUM> with the shroud <NUM>. The outer spray ring <NUM> is also concentric with the inner shroud <NUM> about the longitudinal center axis <NUM> of the spray chamber <NUM>, but is disposed between the outer surface of the inner shroud <NUM> and the side wall of the outer tank <NUM>.

Referring additionally to <FIG>, both the inner spray ring <NUM> and the outer spray ring <NUM> include a plurality of spray nozzles spaced at even intervals thereon. In the present embodiment, each spray ring includes eight nozzles. Referring again to <FIG>, four of the spray nozzles 70a on the inner spray ring <NUM> have spray axes that are directed outwardly at an angle of <NUM>° relative to the longitudinal center axis <NUM> of the spray chamber <NUM>, whereas the spray axes of the remaining four spray nozzles 70b are directed inwardly at an angle of <NUM>° relative to the longitudinal center axis <NUM> of the spray chamber <NUM>. The inwardly angled spray nozzles 70b are configured to make contact with the exhaust plume as it enters the spray chamber <NUM>, thereby producing a rapid drop in temperature of the exhaust plume, whereas the outwardly angled spray nozzles 70a are configured to spray the shroud wall and make contact with the exhaust plume at a lower point within the shroud <NUM>. The outwardly directed nozzles 70a assist in maintaining the temperatures of the shroud <NUM> within the desired range as a large portion of the spray is directed towards the inner surface of the shroud <NUM>. As noted, the nozzles 70c of the outer spray ring <NUM> are vertically oriented and disposed outside the shroud <NUM>. As such, spray from the nozzles 70c of the outer ring <NUM> is initially directed at the outer surface of the shroud <NUM> and the inner surface of the cylindrical side wall of the tank <NUM>. Spray from the outer spray ring <NUM> only comes into contact with the exhaust plume once the spray is below the bottom of inner shroud <NUM>.

Computer modeling for the above described desuperheating super spray chamber <NUM> was conducted with the acceptance criteria being defined by the ASME Boiler & Pressure Vessel Code (BPVC), Section VIII, Div. For an assumed rocket exhaust plume <NUM> temperature of <NUM> (<NUM>,<NUM> degrees Farenheit (°F)) at the entrance port <NUM> of the spray chamber <NUM>, the wall temperature (Twall) of the outer tank <NUM> is to remain below <NUM> (<NUM> °F), the operating pressure is to remain below <NUM> kPa (<NUM> psia), the inlet/outlet mass balance is to be maintained, and fluid exit temperature at the exhaust ports <NUM> should be less than <NUM> (<NUM> °F). In the described preferred embodiment for a rocket exhaust inlet flow of <NUM>/s (<NUM> pounds mass per second (lbm/s)), a spray flow to the inner and outer spray rings <NUM> and <NUM> of <NUM>/s (<NUM> lbm/s) is used, resulting in a total flow of spray of <NUM> lpm (<NUM> gallons per minute (gpm)). To achieve this desired flow, an example nozzle is the Series <NUM> nozzle, manufactured by LechlerUSA, that provides approximately <NUM> lpm (<NUM> gpm) at a pressure of <NUM> kPa (<NUM> psid) across the nozzle, and has a cone angle of <NUM>°. <FIG> show the operational set up of the above described spray chamber <NUM> and the overlapping spray patterns of the inner and outer spray rings <NUM> and <NUM>, respectively.

Referring to <FIG>, computer modeling of the spray chamber described above resulted in the temperatures at all the monitored locations of the spray chamber being below the acceptable ASME BPVC limit of <NUM> (<NUM> °F) after achieving steady-state operating conditions at <NUM> seconds. As shown in <FIG>, the highest temperature encountered in the spray chamber was <NUM> (<NUM> °F) at the wall of the shroud. Referring additionally to <FIG>, the computer analysis also provided that the additional acceptance criteria of maintaining mass flow balance and minimizing pressure losses across the spray chamber were met. Note, the above described spray chamber <NUM> is scalable as needed base on the amount of exhaust to be recovered. For example, the dimensions of the spray chamber, nozzle flow rates, etc., may be adjusted as required. As well, for greater flow rates of exhaust, multiple spray chambers <NUM> may be operated in parallel.

Claim 1:
A desuperheating spray chamber (<NUM>) for use in a rocket exhaust recovery system for a nuclear thermal propulsion rocket, comprising:
a substantially-cylindrical outer tank (<NUM>) with an upper end including an entrance port (<NUM>) and at least one exhaust port (<NUM>) disposed thereon;
a substantially-cylindrical shroud (<NUM>) extending downwardly from an inner surface of the upper end (<NUM>) of the tank (<NUM>);
an inner spray ring (<NUM>) that is disposed within the shroud (<NUM>) about a longitudinal center axis (<NUM>) of the outer tank (<NUM>); and
an outer spray ring (<NUM>) that is disposed between a side wall of the outer tank (<NUM>) and the shroud (<NUM>).