Conversion of nitrogen oxides in the presence of a catalyst supported on a mesh-like structure

• US 6,534,022 B1
• Filed: 10/13/2000
• Issued: 03/18/2003
• Est. Priority Date: 10/15/1999
• Status: Expired due to Term

• Current Assignee: ABB Lummus Global Inc. (ABB Limited)
• Original Assignee: ABB Lummus Global Inc. (ABB Limited)
• Inventors: Chang, Yun-Feng, Trubac, Robert E., Overbeek, Rudolf A., Yeh, Chuen Y., Murrell, Lawrence L., Carlborg, Joakim A., Schmidt, Verena R., Schuh, Lothar
• Primary Examiner(s): TRAN, HIEN THI
• Application Number:
  US09/687,976
• Time in Patent Office: 886 Days
• Field of Search: 423/239.1, 423/213.2, 423/213.5, 210/749, 210/903, 422/171-180
• US Class Current: 422/180
• CPC Class Codes: B01D 2257/402 Dinitrogen oxide
• CPC Class Codes: B01D 2257/502 Carbon monoxide
• CPC Class Codes: B01D 2257/702 Hydrocarbons
• CPC Class Codes: B01D 2257/708 Volatile organic compounds V.O.C.'s
• CPC Class Codes: B01D 53/8631 Processes characterised by a specific device
• CPC Class Codes: B01D 53/864 Removing carbon monoxide or hydrocarbons
• CPC Class Codes: B01D 53/8687 Organic components
• CPC Class Codes: B01D 53/885 Devices in general for catalytic purification of waste gases
• CPC Class Codes: B01D 53/9431 Processes characterised by a specific device
• CPC Class Codes: B01D 53/9477 with catalysts positioned on separate bricks, e.g. exhaust systems
• CPC Class Codes: B01J 21/063 Titanium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 21/066 Zirconium or hafnium; Oxides or hydroxides thereof
• CPC Class Codes: B01J 23/22 Vanadium
• CPC Class Codes: B01J 23/30 Tungsten
• CPC Class Codes: B01J 23/42 Platinum
• CPC Class Codes: B01J 35/56 Foraminous structures having flow-through passages or channels, e.g. grids or three-dimensional monoliths
• CPC Class Codes: B01J 35/58 Fabrics or filaments
• CPC Class Codes: B01J 37/0225 of metal substrates
• CPC Class Codes: B01J 37/0228 in several steps
• CPC Class Codes: F01N 13/0097 the purifying devices are arranged in a single housing
• CPC Class Codes: F01N 2330/10 : Fibrous material, e.g. mineral or metallic wool
• CPC Class Codes: F01N 2330/12 : Metallic wire mesh fabric or knitting
• CPC Class Codes: F01N 2330/14 : Sintered material
• CPC Class Codes: F01N 2330/38 : flow channels with means to enhance flow mixing,(e.g. protrusions or projections)
• CPC Class Codes: F01N 3/281 : Metallic honeycomb monoliths made of stacked or rolled sheets, foils or plates
• CPC Class Codes: F01N 3/2814 : all sheets, plates or foils being corrugated
• CPC Class Codes: F01N 3/2821 : the support being provided with means to enhance the mixing process inside the converter, e.g. sheets, plates or foils with protrusions or projections to create turbulence
• CPC Class Codes: F01N 3/2828 : Ceramic multi-channel monoliths, e.g. honeycombs
• CPC Class Codes: F01N 3/2835 : fibrous
• CPC Class Codes: Y02C 20/10 : of nitrous oxide (N2O)
• CPC Class Codes: Y02P 20/151 : Reduction of greenhouse gas [GHG] emissions, e.g. CO2

Abstract

An apparatus for converting at least one nitrogen oxide, such as NO, NO₂, or N₂O converts oxide in the presence of a catalyst supported on a metal mesh-like structure. The mesh-like structure is preferably fibrous formed of metal or ceramic fibers which may include knitted wire, sintered metal fibers and so on and has a porosity greater than about 85%. The mesh is formed into channels, preferably corrugations, and includes vortex generators, which generate turbulence to create a pressure differential across the mesh, to promote flow of fluids through the mesh pores which normally do not exhibit flow therethrough in the absence of such pressure differential. Preferred embodiments of structured packing and monoliths are disclosed each having a catalyst preferably in the mesh pores and/or coated on the fibers for converting the nitrogen oxide. In one embodiment, corrugated mesh-like sheets are arranged in series with a ceramic solid monolith structure with the corrugated sheets initially receiving the fluid with the at least one nitrogen oxide to be converted and which fluid then flows into the monolith structure to complete the conversion. In other embodiments, the mesh-like structure may have different configurations including a honeycomb arrangement and may include metal, metal and ceramic or ceramic and may be fibrous.

Claims

1. An apparatus for removing at least one nitrogen oxide from a fluid, comprising:

a mesh structure of a porous material having internal pores and opposing sides, the average pore size of the material being sufficiently small that normally fluid flow is not exhibited through the porous material in the presence of negligible pressure differential thereacross on opposite surfaces, said mesh structure having a porosity of greater than 85%, the opposing sides forming channels, each channel having a fluid receiving inlet and a fluid outlet, the received fluid for flowing through the channels along the surfaces of the material to and through said outlets from the respective inlet, the pores being in fluid communication with each other and with the channels externally the material at each said side, said material including turbulence generator means which is one piece with said material for creating a pressure differential across the opposing sides in said flowing fluids, said pressure differential for causing the flowing fluids to flow through the pores transversely through the material from one side to the other side of the material to promote contact between the fluids flowing on the opposite sides of the material and to promote contact with the material in the pores over essentially the entire surface of the material; and

a nitrogen oxide conversion catalyst supported on the material on the opposing surfaces and in said pores for reacting with said fluids as the received fluids flow through the channels and through the pores from one side to the opposite side of the material over essentially the entire surface of the material.

2. The apparatus of claim 1 including a series arrangement of said mesh structure and a monolith honeycomb structure.

3. The apparatus of claim 2 wherein the mesh structure and monolith structure are arranged so that fluid initially flows into the mesh structure and then into the monolith structure.

4. The apparatus of claim 1 wherein the mesh structure is corrugated.

5. The apparatus of claim 1 wherein the mesh structure comprises adjacent corrugated sheets, each sheet with parallel corrugations, the corrugations of adjacent sheets at 90°

relative to each other and at an angle α

in the range of about 45°

to about 70°

to the given direction.

6. The apparatus of claim 1 wherein the mesh structure is fibrous and made of one of metal fibers, ceramic fibers, and metal/ceramic fibers.

7. The apparatus of claim 2 wherein the monolith structure is made of one of solid ceramic material, metal fibers, ceramic fibers, and metal/ceramic fibers.