Contact tray for a mass transfer column

1. A contact tray for a mass transfer column comprising

a tray deck for receiving a flow of liquid thereon, said tray deck having a plurality of laterally unencumbered orifices for passage of an ascending vapor therethrough; and

a plurality of valve covers, each said valve cover being mounted over a respective one of said orifices and having a central portion disposed in spaced relation to said tray deck and over a respective orifice, a pair of sloped legs at opposite ends, and a pair of guide vanes extending laterally and downwardly from said central portion towards said tray deck for deflecting a majority of the vapor ascending through a respective orifice towards said tray deck.

2. A contact tray as set forth in claim 1 wherein at least some of said valve covers have a pair of panels, each said panel extending between a respective one of said pair of legs and a respective one of said pair of guide vanes for deflecting a part of the vapor ascending through a respective orifice towards said tray deck.

3. A contact tray as set forth in claim 2 wherein each said valve cover has means for engaging said tray deck to prevent lifting of said respective valve cover from said tray deck.

4. A contact tray as set forth in claim 3 wherein said means includes a deformable tab extending from at least one of said legs through a slot in said tray deck to abut an underside of said tray deck.

5. A contact tray as set forth in claim 1 further comprising an opening in a selected one of said central portion and said legs for passage of vapor therethrough.

6. A contact tray as set forth in claim 1 wherein each said guide vane is spaced from said deck in a range of from 3 to 10 mm.

7. A contact tray as set forth in claim 1 further comprising a plurality of de-entrainment devices, each said de-entrainment device extending from a respective valve cover below said tray deck and having a deflector in vertical alignment with a respective orifice in said tray deck.

8. A contact tray as set forth in claim 7 wherein said deflector is downwardly angled and includes a pair of longitudinally extending blades disposed in angular relation to each other.

9. A contact tray as set forth in claim 7 wherein said deflector is horizontally disposed and includes a plurality of slots and at least one downwardly inclined finger within each slot.

10. A contact tray as set forth in claim 7 wherein each de-entrainment device further has a vertically disposed leg connecting said deflector to a respective valve cover.

11. A contact tray as set forth in claim 1 wherein each said orifice in said tray deck has a central section and at least a pair of end sections of smaller width than said central section extending from opposite ends of said central section and each said leg of each said valve cover extends into a respective end section of a respective orifice.

12. A contact tray as set forth in claim 1 wherein said tray deck includes at least one slot adjacent a respective orifice and each said valve cover has a leg extending from said central portion into said slot.

13. A valve cover for a mass transfer column comprising

a central portion for disposition in spaced relation to an orifice for passage of an ascending flow of vapor in a tray deck;

a pair of legs extending downwardly from opposite ends of said central portion; and

a pair of guide vanes extending laterally and downwardly from said central portion for deflecting a majority of the vapor ascending through a respective orifice towards the tray deck, each said guide vane being spaced from the tray deck in a range of from 3 to 10 mm.

14. A valve cover as set forth in claim 13 further comprising a pair of panels, each said panel extending between a respective one of said pair of legs and a respective one of said pair of guide vanes for deflecting a part of the vapor ascending through a respective orifice towards the tray deck.

15. A valve cover as set forth in claim 13 further comprising a first opening in said central portion and a second opening in one of said legs.

16. A valve cover as set forth in claim 13 further comprising a deformable tab extending from at least one of said legs for passage through a slot in a tray deck for abutting an underside of the tray deck upon deformation thereof.

17. A valve cover as set forth in claim 13 further comprising a de-entrainment device extending downwardly from one of said legs.

18. A valve cover as set forth in claim 17 wherein said de-entrainment device has a downwardly angled deflector in vertical alignment said central portion.

19. A valve cover as set forth in claim 18 wherein said deflector includes a pair of longitudinally extending blades disposed in angular relation to each other.

20. A valve cover as set forth in claim 18 wherein said de-entrainment device has a vertically disposed leg connecting said deflector to one of said legs.

21. In combination,

a tower disposed on a vertical axis;

a plurality of horizontal tray decks disposed in spaced vertical relation within said tower for receiving flows of liquid thereon, each said tray deck having a plurality of laterally unencumbered orifices for passage of an ascending vapor therethrough; and

a plurality of valve covers mounted on each respective tray deck, each said valve cover having a central portion disposed in spaced relation to a respective orifice in a respective tray deck, a pair of sloped legs at opposite ends and a pair of guide vanes extending laterally and downwardly from said central portion towards and in spaced relation to said respective tray deck for deflecting a majority of the vapor ascending through a respective orifice towards said respective tray deck, each said guide vane being spaced from said respective tray deck in a range of from 3 to 10 mm.

22. The combination as set forth in claim 21 further comprising a plurality of de-entrainment devices, each said de-entrainment device extending from a respective valve cover below a respective tray deck and having a deflector in vertical alignment with a respective orifice in said respective tray deck.

23. The combination as set forth in claim 22 wherein each de-entrainment device has a vertically disposed leg connecting said deflector to one of said legs of a respective valve cover.