Fluid flow conditioner
A device and method for conditioning media flowing within a conduit enabling sensors placed within short straight run distances to measure media flow with improved accuracy employing a thermal flow instrument. A flow conditioner downstream of a media flow measuring transducer has walls that diverge in the flow direction to optimize readings of the media flow from the transducer.
1. A fluid flow conditioner device for use with a thermal mass flow instrument having at least one thermowell having a sensing element therein configured to be arranged in the media flow in a conduit, the media within the conduit flowing in a predetermined direction, the sensing element being heated for at least a portion of the time that the media is flowing in the conduit, the device comprising:
a first wall element arranged a predetermined distance downstream from said at least one thermowell, said first wall element being orientated at an angle with respect to the media flow direction, the distance between said first wall element and said at least one thermowell being sufficiently close to cause the media flowing between said at least one thermowell and said first wall element to be substantially free or turbulence.
2. The device of claim 1 , the thermal mass flow instrument further comprising a second thermowell having a sensing element therein, said second thermowell being spaced from said at least one thermowell, said device further comprising:
a second wall element positioned at an angle with said first wall element to form a pair of diverging walls having a wedge-shaped structure having a center positioned generally equidistance from said thermowells, the distance between said walls and the respective thermowells being sufficiently close to cause the media flowing between each said thermowell and each respective said wall element to be substantially free of turbulence.
3. The device of claim 2 , and further comprising a shroud element partially encompassing said wedge-shaped structure and said thermowells, said shroud element having passageways therethrough to enable the media to flow through while encountering said wedge-shaped structure and said thermowells.
4. The device of claim 3 , wherein said shroud element is formed with opposing, spaced walls defining an upstream opening and wherein said diverging walls of said wedge-shaped structure have distal ends that are spaced from said spaced walls of said shroud downstream of said thermowells by a predetermined distance.
5. The device of claim 3 , wherein said thermowells and said wedge-shaped structure extend substantially coextensively into the interior of said shroud.
6. The device of claim 2 , wherein said center of said pair of diverging walls meet at an angle of about 90°-140° downstream in the flow direction.
7. The device of claim 6 , wherein the line formed by said pair of diverging walls is normal to the flow direction.
8. The device of claim 2 , wherein at least one of said thermowells includes a heated sensor and the other includes a reference sensor, at least said heated sensor thermowell being spaced from said at least one of said diverging walls by a predetermined distance.
9. The device of claim 2 , and further comprising a shroud element partially encompassing said wedge-shaped structure and said thermowells, said shroud having an upstream opening therein, the upstream opening being formed to permit the media to flow into said shroud and to impinge upon said thermowells and said wedge-shaped structure.
10. The device of claim 9 , wherein said shroud element is formed with opposing, spaced walls defining the upstream opening and wherein said diverging walls of said wedge-shaped structure, have distal ends that are spaced from said spaced walls of said shroud downstream of said thermowells by a predetermined distance.
11. The device of claim 9 , wherein said thermowells and said wedge-shaped structure extend substantially coextensively into the interior of said shroud.
12. The device of claim 1 , wherein said wall element is arranged at an angle of about 45°-70° with respect to the flow direction of the media.
13. A method for conditioning media flowing in a predetermined direction within a conduit having a thermal mass flow instrument therein comprising at least one thermowell with a sensing element arranged in the media flow in the conduit, the method comprising:
installing a first wall adjacent to and downstream from the at least one thermowell at an angle with respect to the media flow direction and sufficiently close to the at least one thermowell to cause the media flow to be substantially free of turbulence as it flows past the at least one thermowell.
14. The method of claim 13 wherein:
the at least one thermowell comprises two spaced parallel thermowells having sensing elements therein where one of the thermowells is heated; and
installing a second wall adjacent to and downstream from a respective thermowell, the first and second walls being joined together to form a pair of diverging walls having a wedge-shaped structure having a center positioned generally equidistant from the spaced thermowells.
15. The method of claim 14 , and further comprising channeling the flowing media around and past the wedge-shaped structure and the thermowells by means of a shroud partially surrounding the wedge-shaped structure and the thermowells, the shroud being formed with an opening upstream from the thermowells in the flow direction.
16. The method of claim 15 , wherein the shroud is formed with opposing, spaced walls defining the upstream opening, and further comprising positioning the pair of diverging walls of the wedge-shaped structure such that the pair of diverging walls end adjacent to and spaced from the spaced walls of the shroud by a predetermined distance.
17. The method of claim 14 , wherein the center is formed at upstream ends of the pair of diverging walls in the flow direction and the wedge-shaped structure has an angle of about 90°-140° facing downstream in the flow direction.
18. The device of claim 1 , wherein the first wall element has a downstream end and an upstream end, the upstream end being located generally laterally with respect to the at least one thermowell in relation to the direction of media flow.
19. The device of claim 2 , wherein the center of the wedge-shaped structure is located generally between the first and second thermowell.
20. The device of claim 2 , wherein the center of the wedge-shaped structure is located at least partially between the first and second thermowell.