Apparatus and method for gaseous emissions treatment with enhanced catalyst distribution
An assembly for treating gaseous emissions includes a substrate body having cells for the passages of emissions gas. Lengths of metal wire are located in selected ones of the cells and an induction heating coil is mounted adjacent the substrate body for generating a varying electromagnetic field for inductive heating of the assembly including gaseous emissions passing along the cells. Within the cells, parts of the cell walls and parts of the wire surfaces are exposed to the passage of the gaseous emissions and both the cell wall parts and the wire surface parts have pollution treating catalyst at their surfaces.
1. An assembly for treating gaseous emissions comprising a substrate body having a plurality of cells for the passage of emissions gas, the cells having internal walls, respective metal wires located in each of a first set of the plurality of cells, and an induction heating coil mounted adjacent the substrate body for generating a varying electromagnetic field, thereby inductively to heat the metal wires and thereby to heat the substrate body, the metal wires and the internal walls of the cells within which the metal wires are contained having catalyst material at surfaces thereof for use in treating emissions gas passing through the cells.
2. The assembly as claimed in claim 1 , wherein such internal walls bear a layer of the catalyst material.
3. The assembly as claimed in claim 2 , wherein the layer is an applied layer.
4. The assembly as claimed in claim 2 , wherein the layer of catalyst metal is alloyed with the metal of the wire.
5. The assembly as claimed in claim 1 , wherein the metal wires have one of a hollow cross section and an open cross-sectional shape, being one of a generally L, C, U and V-shape cross-section.
6. The assembly as claimed in claim 1 , wherein the metal wires are retained within receptive ones of the cells by a friction fit between the wires and the interior walls of the cells in which the wires are contained.
7. The assembly as claimed in claim 1 , further comprising a layer of adhesive between the metal wires and the interior walls of the cells within which the wires are contained, thereby to establish an adhesive fit between the wires and the cell walls.
8. The assembly as claimed in claim 1 , the locations of the metal wires selected to obtain a generally uniform electromagnetic flux density in at least a part of the substrate body.
9. The assembly as claimed in claim 1 , the assembly having a front for entry of gaseous emissions to be treated and a back for exit of treated gaseous emissions, the substrate body having a relatively higher concentration of metal per unit volume of the substrate body near the front than near the back.
10. The assembly as claimed in claim 1 , at least some of the metal wires being wire segments extending only partially along the lengths of the cells.
11. The assembly as claimed in claim 1 , the substrate body having a front for entry of gaseous emissions to be treated and a back for exit of treated gaseous emissions, at least some of the metal wires projecting from the front of the substrate body.
12. The assembly as claimed in claim 1 , the metallic composition of at least one of the metal wires being different from the metallic composition of at least one other of the metal wires.
13. The assembly as claimed in claim 1 , the concentration of metal wire per unit volume of the substrate body selected to obtain a desired level of electromagnetic flux density near the center of the substrate body.
14. The assembly as claimed in claim 1 , the substrate body having a front for entry of gaseous emissions to be treated and a back for exit of treated gaseous emissions, the concentration of metal of the metal wires per unit volume of the substrate body selected to obtain a desired level of electromagnetic flux density near the front of the substrate body.
15. The assembly as claimed in claim 1 , the substrate body made of a ceramic honeycomb material.
16. The assembly as claimed in claim 1 , the metal of the wires being a ferromagnetic metal.
17. A process for treating gaseous emissions using an assembly comprising an induction heating coil mounted adjacent a substrate body, the substrate body having a plurality of cells for the passage of emissions gas, the cells having internal walls, and respective metal wires located in each of a first set of the plurality of cells, the metal wires and the internal walls of the cells within which the wires are contained having a catalyst material at surfaces thereof, the method comprising generating a varying electromagnetic field at the coil thereby to cause induction heating of the metal wires, and thereby to heat the substrate body, and treating gaseous emissions with the catalyst material.
18. The process as claimed in claim 17 , further comprising generating the varying electromagnetic field when an engine which is the source of the emission gases is operating and when the substrate body is below a predetermined threshold temperature.
19. The process as claimed in claim 17 , further comprising generating the varying electromagnetic field for an engine which is to be the source of the emission gases before start-up of the engine.