Method and apparatus for no2-based regeneration of diesel particulate filters using recirculated NOX

Abstract

In a method for performing NO2-based regeneration of a diese! particulate filter (DPF) using recirculated NOx, the DPF is regenerated by oxidizing soot in the DPF with NO2 so that CO, CO2, and NO are formed, at least some NOx is recirculated from a takeoff point to a point upstream of the takeoff point. NO2 can be formed by reacting the recirculated NO with 02. During regeneration of the DPF, at least some of the NO2 that oxidizes soot in the DPF is recirculated ISI 02 or formed from recirculated NO that is reacted with 02 to form NO2. An exhaust aftertreatment system for performing NO2-based regeneration of a diesel particulate filter (DPF) using recirculated NOx is also disclosed.

Description

[0001]The present application is related to commonly assigned, copending application Ser. No. ______ (Attorney Docket No 000009-260) entitled METHOD AND APPARATUS FOR REGENERATING A CATALYZED DIESEL PARTICULATE FILTER (DPF) VIA ACTIVE NO2-BASED REGENERATION WITH ENHANCED EFFECTIVE NO2 SUPPLY, filed on the same date as the present application, and claims the benefit of U.S. Provisional Application 61 / 063,900, filed Feb. 7, 2009, entitled METHOD FOR MAXIMIZING SOOT REDUCTION CAPACITY OF NO2 REACTANT FOR ACTIVE NO2 REGENERATION OF PARTICULATE FILTER.BACKGROUND AND SUMMARY[0002]The invention relates to methods and apparatus for regeneration of diesel particulate filters (DPFs), that is, removal of accumulated particulate matter or soot from the DPF, and more particularly to methods and apparatus involving an oxidation reaction with NO2.[0003]The most common method for removal of soot from a DPF is oxidation of the trapped soot to produce gaseous products (CO2 and CO) which can pass thro...

AI Technical Summary

Benefits of technology

"The patent describes a method and system for regenerating diesel particulate filters (DPFs) using recirculated NOx. The method involves oxidizing soot in the DPF with NO2 to form CO, CO2, and NO, which can then pass through the filter and be released into the atmosphere. The recirculated NOx can be formed by reacting O2 with NO2 or by using a catalyst to produce NO2 from NO. The method can be used in combination with other regeneration methods, such as O2-based or NO2-based regeneration, and can help to improve the performance and durability of exhaust aftertreatment devices downstream of the DPF. The patent also describes an exhaust aftertreatment system that includes a DPF and a conduit for recirculating NOx to oxidize soot in the DPF. The technical effects of the patent include improved regeneration efficiency, reduced temperature requirements, and the ability to regenerate in a wider range of engine operating regimes."

Problems solved by technology

The primary limitation of passive NO2-based regeneration is its inability to guarantee adequate regeneration of the DPF in all applications.

The primary limitations of O2-based regenerations are lower maximum DPF soot loading levels, which must be observed, and a significantly higher temperature requirement than is necessary for NO2-based regeneration.

The higher temperature requirement, as well as the need for more frequent regenerations, can lead to deterioration in the performance and durability of all affected exhaust aftertreatment devices, including those downstream of the soot filtration and regeneration components, such as an SCR system.

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