Concentric catalytic combustor

1. A catalytic combustor comprising:

a tubular pressure boundary element having a longitudinal flow axis separating a first portion of a first fluid flow from a second portion of the first fluid flow and comprising a wall having a plurality of separate, longitudinally oriented flow paths annularly disposed within the wall and conducting respective portions of a second fluid flow therethrough; and

a catalytic material disposed on a surface of the pressure boundary element exposed to at least one of the first and second portions of the first fluid flow.

2. The catalytic combustor of claim 1 , wherein: the first fluid flow comprises a combustible fluid; and the second fluid flow comprises a cooling fluid containing no combustible fuel.

3. The Catalytic combustor of claim 2 , wherein the surface comprises an inner diameter surface of the pressure boundary element.

4. The catalytic combustor of claim 2 , wherein the surface comprises an outer diameter surface of the pressure boundary element.

5. The catalytic combustor of claim 1 , wherein each of the plurality of separate flow paths comprises a hexagonal cross section.

6. The catalytic combustor of claim 1 , wherein each of the plurality of separate flow paths comprises a rectangular cross section.

7. The catalytic combustor of claim 1 , wherein each of the plurality of separate flow paths comprises a corrugated cross section.

8. The catalytic combustor of claim 1 , wherein the plurality of separate flow paths comprise a first annular ring of spaced apart channels and a second annular ring of spaced apart channels formed radially outward of the first ring so that the channels of the second annular ring fit at least partially radially inward within corresponding spaces formed by the first annular ring of channels.

9. A catalytic combustor comprising:

a plurality of concentric tubular pressure boundary elements having respective longitudinal flow axes forming a plurality of concentric annular spaces conducting respective portions of a combustible fluid flow; each of the tubular pressure boundary elements comprising a wall comprising a plurality of separate, longitudinally oriented flow paths annularly disposed within the wall and conducting respective portions of a cooling fluid flow therethrough; and

a catalytic material disposed on respective surfaces of the pressure boundary elements and exposed to the respective portions of the combustible fluid flow.

10. The catalytic combustor of claim 9 , wherein the catalytic material is disposed on one surface of adjacent elements having opposed surfaces forming an annular space there between.

11. The catalytic combustor of claim 9 , wherein the catalytic material is disposed on both surfaces of adjacent elements having opposed surfaces forming an annular space there between.

12. The catalytic combustor of claim 9 , further comprising a manifold assembly attached to an upstream end of the combustor, the manifold assembly comprising a radial passageway receiving the combustible fluid flow and conducting the combustible fluid flow into annular spaces formed in the manifold assembly in fluid communication with respective annular spaces formed by the plurality of concentric tubular pressure boundary elements.

13. The catalytic combustor of claim 12 , the manifold assembly comprising a central opening receiving the combustible fluid flow and conducting the combustible fluid flow into the radial passageway.

14. The catalytic combustor of claim 13 , the manifold assembly comprising an axial passageway remote from the radial passageways receiving the cooling fluid flow and conducting the cooling fluid flow into the plurality of separate flow paths annularly disposed within each of the pressure boundary elements.

15. A gas turbine engine comprising the combustor of claim 9 .

16. A method for using a combustor to oxidize a combustible fluid flow, the method comprising:

providing a plurality of concentric tubular pressure boundary elements having respective longitudinal flow axes forming a plurality of concentric annular spaces conducting respective portions of a combustible fluid flow; each of the tubular pressure boundary elements comprising wall comprising a plurality of separate, longitudinally oriented flow paths annularly disposed within the wall and conducting respective portions of a cooling fluid flow therethrough;

providing a catalytic material on respective surfaces of the pressure boundary elements and exposed to the respective portions of the combustible fluid flow;

conducting respective portions of the combustible fluid flow through the plurality of concentric annular spaces to expose the combustible fluid flow to the catalytic material and produce a partially oxidized fluid flow; and

conducting respective portions of the cooling fluid flow through the flow paths annularly disposed within the wall to provide cooling of the combustible fluid flow while the combustible flow is being conducted through the annular spaces.

17. A catalytic combustor comprising:

a plurality of catalytic combustion modules, each module comprising a plurality of concentric tubular pressure boundary elements having respective longitudinal flow axes forming a plurality of concentric annular spaces conducting respective portions of a combustible fluid flow, each of the tubular pressure boundary elements comprising a wall having a plurality of separate, longitudinally oriented flow paths annularly disposed within the wall and conducting respective portions of a cooling fluid flow therethrough;

one of the plurality of the modules disposed along a central axis of the combustor;

remaining ones of the plurality of modules circumferentially disposed about the central axis radially outward of the one of the plurality of modules; and

each module comprising a pilot burner disposed in a central region of the respective module.

18. A catalytic combustor comprising:

a plurality of catalytic combustion modules, each module comprising a plurality of concentric tubular pressure boundary elements having respective longitudinal flow axes forming a plurality of concentric annular spaces conducting respective portions of a combustible fluid flow, each of the tubular pressure boundary elements comprising a wall having a plurality of separate, longitudinally oriented flow paths annularly disposed within the wall and conducting respective portions of a cooling fluid flow therethrough; and

each module circumferentially disposed about a central axis radially outward of a central region of the combustor.

19. The catalytic combustor of claim 18 , further comprising a pilot burner disposed in the central region.