Method and apparatus for gaseous mixing in a diesel exhaust system

Abstract

A mixing device and method for a diesel exhaust system is disclosed having a chamber, a mixer within the chamber, and an injection tube supported on the mixer within the chamber. The mixer is positioned within the chamber adjacent an inlet and includes a plurality of angled blades to effect turbulent flow in a diesel exhaust stream entering the chamber through the inlet. The injection tube includes a plurality of injection points (e.g., openings) for discharging a reagent, such as gaseous ammonia (NH3), into the exhaust stream. The injection tube is curved, and more specifically it is coiled with the injection points spread along the length of the tube in order to deliver reagent across a section of the chamber perpendicular to the exhaust stream flow.

Description

TECHNICAL FIELD OF THE INVENTION[0001]The present invention relates to an apparatus and method for treating and mixing diesel exhaust in a diesel exhaust system. Particularly, the present invention provides methods and apparatus for injecting reagent into a diesel exhaust stream to reduce nitrogen oxides (NOx) without increasing the packing space of the exhaust system.BACKGROUND OF THE INVENTION[0002]Diesel engines are efficient, durable and economical. Diesel exhaust, however, can harm both the environment and people. To reduce this harm, governments, such as the United States and the European Union, have proposed stricter diesel exhaust emission regulations. These environmental regulations require diesel engines to meet the same pollution emission standards as gasoline engines.[0003]Typically, to meet such regulations and standards, systems require equipment additions and modifications. Additional equipment can often lead to additional weight and / or additional packaging length.[00...

AI Technical Summary

Benefits of technology

[0007]There is disclosed herein an improved diesel exhaust treatment system and method which avoid disadvantages of prior devices and methods, while affording additional structural and operating advantages.

Problems solved by technology

Diesel exhaust, however, can harm both the environment and people.

Additional equipment can often lead to additional weight and / or additional packaging length.

Such engines are said to run “lean” or on a “lean mixture.” However, the increase in fuel efficiency is offset by the creation of undesirable pollution emissions in the form of nitrogen oxides (NOx).

However, selective catalytic reduction and the use of aqueous urea involve many disadvantages, including added packaging weight and added packaging length to the exhaust system, as well as the highly corrosiveness and poor lubricity of aqueous urea.

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