An Aerodynamically Regenerated Diesel Particulate Trap Coupled to an Electric Soot Incinerator with Dual Wall-Flow Filters

The development of a soot incinerator with dual ceramic filters and an electric strip heater is discussed herein. The incinerator is designed to operate in series with a diesel particulate trap developed previously (1).¹ The particulate trap consists of a primary ceramic monolith which serves as the filtering device. Once the primary monolith has collected enough soot from the exhaust flow to induce a substantial amount of back pressure to the engine, it is cleaned aerodynamically using short pulses of compressed air. The soot is then forced through a reed valve and into the incinerator chamber, where some of the particulates come in contact with an electric strip heater and burn. The regeneration air exits the incinerator through two secondary ceramic wall-flow rectangular filters, where any unburned particulates are retained. Filtered regeneration air is, thus, released to the atmosphere. In order to periodically clean both secondary filters, and expose the trapped soot particles again to the electric burner for further incineration, each secondary filter is subjected to aerodynamic cleaning in an alternating fashion. The incinerator system was designed to effectively burn the particulates, while maintaining flow-through characteristics for the regeneration air to achieve maximum cleaning of the main monolith.

Since additional compressed air is used to clean the two secondary filters, methods for minimizing the overall air consumption were investigated. To minimize release to the atmosphere of any CO emissions, generated during the combustion of soot, the effluent of the incinerator was channelled back to the intake of the engine. The complete system of the diesel particulate trap and the electric incinerator has been tested in the laboratory for its effectiveness to capture and destroy diesel soot emissions.