Producing ammonium carbamate and reducing nitrogen oxides
AssigneeLoughborough University
InventorsJonathan WILSON, Graham HARGRAVE
Life of this patent
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Abstract
A process for reducing nitrogen oxides in an exhaust stream, such as a vehicle exhaust stream, and apparatus for carrying out the process. The process comprises providing a first composition comprising aqueous urea, a second composition comprising ammonium carbamate and an exhaust stream comprising nitrogen oxides. A process for producing the ammonium carbamate is also provided. The second composition may be introduced into the exhaust stream (10) when the exhaust stream has a temperature below a threshold temperature and the first composition may be introduced into the exhaust stream when the exhaust stream has a temperature at or above the threshold temperature.
Claims24
A process for reducing nitrogen oxides in an exhaust stream, the process comprising
- providing a first reservoir having the first composition therein, the first composition comprising aqueous urea;
- transferring a portion of the first composition along a flow path, the flow path being in communication with a second reservoir;
- heating the portion of the first composition to produce a mixture comprising ammonia, carbon dioxide and water;
- the heating taking place in the flow path or in the second reservoir;
- cooling the mixture to generate a second composition, the second composition comprising aqueous ammonium carbamate and the cooling taking place in the flow path or in the second reservoir;
- introducing the second composition from the second reservoir into an exhaust stream comprising nitrogen oxides.
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An apparatus for reducing nitrogen oxides (NOx) in an exhaust stream comprising nitrogen oxides, the apparatus comprising:
- a first source of a first composition comprising urea and water, the first source comprising a first reservoir for the first composition;
- a second source of a second composition comprising ammonium carbamate, the second source comprising a second reservoir for the second composition;
- a passage for the exhaust stream;
- in which the apparatus comprises a flow control apparatus arranged to:
- selectively couple the second source to the passage to introduce the second composition into the exhaust stream;
- and
- selectively couple the first source to the passage to introduce the first composition into the exhaust stream.
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Dependencies are inferred from the claim text.