Segregated catalyzed metallic wire filter for diesel soot filtration

Abstract

A filter for removing soot particles from the exhaust gas of a diesel engine comprises a plurality of hollow channels which contain therein a metal mesh. The metal mesh can be coated with an oxidation catalyst to promote ignition of the soot particles and regeneration of the metal mesh for filtering the soot particles. The metal mesh can optionally be removed from the hollow channels and replaced with regenerated or new metal mesh if desired.

Description

FIELD OF THE INVENTION [0001] This invention relates to diesel engine exhaust gas treatment and more particularly to the filtering of particulates from diesel engine exhaust gases using a catalyzed filter. BACKGROUND OF THE INVENTION [0002] Diesel engine exhaust is a heterogeneous mixture which contains not only gaseous emissions such as carbon monoxide (“CO”), unburned hydrocarbons (“HC”) and nitrogen oxides (“NOx”), but also condensed phase materials (liquids and solids) which constitute the so-called particulates or particulate matter (“PM”). The total particulate matter (“TPM”) emissions are comprised of three main components. One component is the solid, dry, solid carbonaceous fraction or soot. This dry carbonaceous matter contributes to the visible soot emissions commonly associated with diesel exhaust. A second component of the TPM is the soluble organic fraction (“SOF”). The soluble organic fraction is sometimes referred to as the volatile organic fraction (“VOF”), which ter...

AI Technical Summary

Benefits of technology

[0015] A diesel soot filter is provided comprising a plurality of parallel channels that are composed of a metallic mesh to trap soot particles as the diesel exhaust gas passes through the channels. The filtering channels can be arranged such as in a canister such that smaller by-pass gas channels are formed between the filtering channels. The by-pass channels allow the exhaust gas to pass therethrough in the event that soot accumulation in the main filtering channels exceeds the burning rate of the accumulated soot. The reduced gas flow through the by-pass channels reduces the back pressure and keeps the vehicle running until a favorable regeneration of the filter is achieved. The wire mesh can be removed from the channels and replaced with new metal mesh, and / or the channels containing the metal mesh may also be removed and replaced if needed to renew soot removal.

Problems solved by technology

As the mass of collected particulates increases, the flow rate of the exhaust gas through the filter is usually impeded, whereby an increased back pressure is encountered within the filter and reduced engine efficiency results.

However, experience has shown that in normal diesel engine operation, the temperature in the exhaust system varies substantially under different conditions of engine load and speed and that the temperatures in the filter hardly ever reach the 510° C. temperature level required to incinerate the trapped particulate.

Wallflow filters provide an answer to the filtration requirement, yet there remains the residual problem of achieving a reliable and repeatable method of cleaning the filter.

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