Exhaust purification with on-board ammonia production

Abstract

A power source is provided for use with selective catalytic reduction systems for exhaust-gas purification. The power source has a first cylinder group fluidly connected to a first air-intake passage and a first exhaust passage, wherein the first air-intake passage is configured to provide air at a first set of characteristics. The power source also has a second cylinder group fluidly connected to a second air-intake passage and a second exhaust passage, wherein the second air-intake passage is configured to provide air at a second set of characteristics different from the first set of characteristics. An ammonia-producing catalyst may be disposed within the first exhaust passage and configured to convert at least a portion of a fluid in the first exhaust passage into ammonia. Further, a merged exhaust passage may be configured to connect the first exhaust passage and the second exhaust passage downstream of the ammonia-producing catalyst to facilitate a reaction between ammonia and NOx to at least partially remove NOx from the merged exhaust passage.

Description

[0001] This application is a continuation-in-part of U.S. patent application Ser. No. 10 / 982,921, filed Nov. 8, 2004, which is hereby incorporated by reference.U.S. GOVERNMENT RIGHTS [0002] This invention was made with government support under the terms of Contract No. DE-FC05-00OR22806 awarded by the Department of Energy. The government may have certain rights in this invention.TECHNICAL FIELD [0003] This disclosure pertains generally to exhaust-gas purification systems for engines, and more particularly, to selective catalytic reduction systems with on-board ammonia production. BACKGROUND [0004] Selective catalytic reduction (SCR) provides a method for removing nitrogen oxides (NOx) emissions from fossil fuel powered systems for engines, factories, and power plants. During SCR, a catalyst facilitates a reaction between exhaust-gas ammonia and NOx to produce water and nitrogen gas, thereby removing NOx from the exhaust gas. [0005] The ammonia that is used for the SCR system may be ...

AI Technical Summary

Benefits of technology

The present patent is about a power source for use with selective catalytic reduction systems for exhaust-gas purification. The power source has two cylinder groups that provide air at different sets of characteristics. An ammonia-producing catalyst is placed in the first exhaust passage to convert some of the air into ammonia. A merged exhaust passage is used to connect the two exhaust passages and allow the ammonia to react with NOx to remove it from the exhaust gas. The power source can supply air to two different air-intake passages and two different exhaust passages, allowing for more efficient purification of exhaust gas. The method of operating the power source involves supplying air at different sets of characteristics to the two cylinder groups, converting at least some of the air to ammonia, and merging the two exhaust streams to form a merged exhaust stream. The technical effect of this patent is a more efficient and effective purification of exhaust gas from selective catalytic reduction systems.

Problems solved by technology

Because of the high reactivity of ammonia, storage of ammonia can be hazardous.

Further, on-board production of ammonia can be costly and may require specialized equipment.

For example, an engine may function less efficiently and with lower power output when rich combustion occurs in one cylinder group.

Furthermore, using the method of the '542 patent, it may be more difficult to provide adequate and controlled air intake to both cylinder groups, and the two cylinder groups, operating as described in the '542 patent, may cause significant engine vibration.

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