NYC to retrofit sanitation vehicles with diesel particulate filters

8 January 2002

The New York City Department of Sanitation today launched a pilot project to voluntarily retrofit a portion of the City’s sanitation truck fleet with diesel particulate filters (DPF) and reduce particulate matter (PM) emissions by up to 90%. The project is conducted in partnership with Cummins Inc. and the Northeast States for Coordinated Air Use Management (NESCAUM). The Department of Sanitation plans to retrofit approximately 260 sanitation trucks over the next three years with DPFs and has acquired four compressed natural gas street sweepers with the financial assistance of the project participants.

This project is one of only a few such retrofit programs in the country. While diesel particulate filters are commercially viable for higher exhaust temperature applications, the technology is facing more technical challenges in low exhaust temperature applications, such as on sanitation vehicles. Although proven in many applications, diesel particulate filters are just being introduced into the US market. This is largely due to several factors: (1) a lack of legislative requirements, (2) limited availability of ultra low sulfur diesel fuel and (3) scarce cost incentives for the retrofit technology. These aside, in 2007 all new diesel trucks will face stricter emissions standards that are expected to force the use of particulate filter technology.

The project’s filters passively regenerate by catalytically oxidizing captured particulates upon reaching a sufficient operating temperature in the vehicle exhaust. The project goal is to prove that filters can be successfully applied to sanitation vehicles by overcoming the vehicles’ traditional low exhaust temperatures. This is being achieved by operating the pilot trucks on ultra low sulfur diesel fuel and boosting the exhaust temperature entering the filter by insulating the exhaust system. Sanitation trucks normally do not exhibit exhaust temperatures conducive to passive filter regeneration. Without regeneration, particles continuously accumulate on the filter, which can lead to an increase in backpressure, potentially affecting engine performance and the engine itself. To minimize such risks, Cummins will install devices that will depower the engine upon sensing excessive backpressure. The ultra low sulfur fuels (30 ppm S max.) will be supplied by Sprague Energy.

Four trucks have entered a pilot testing stage to evaluate the feasibility of the DPF technologies. The trucks will undergo extensive performance and emissions testing and will be carefully monitored over the course of the winter. The program is testing two alternative filter technologies manufactured by Johnson Matthey, Inc. (CRT filter) and by Engelhard Corporation (catalyzed DPF). Based on the performance, durability and emission testing of the filters, a single supplier will be chosen for the remaining program vehicles. Fleetguard Nelson, a division of Cummins, designed and manufactured the project’s exhaust hardware including the filter assembly. The filters were installed at Cummins Metropower with engineering supervision provided by Cummins Inc. NESCAUM is the project coordinator with technical guidance provided by Cummins Inc., the vehicles’ engine manufacturer, and M.J. Bradley & Associates, an environmental consulting firm in the advanced vehicle field. Peer review is provided by the New York State Department of Environmental Conservation.

The four CNG street sweepers, designed and custom built by the Johnston Sweeper Company and deployed by the Department of Sanitation earlier this year, have lower exhaust emissions of particulate, NOx and VOC when compared to their diesel counterpart. These vehicles employ a ULEV rated CNG engine, manufactured by Cummins, and are equipped with oxidation catalysts to further reduce emissions. These new street sweepers will be evaluated for operation and emission reduction performance.

This project is being undertaken pursuant to the 1998 Consent Decrees between the US engine manufacturers and the US EPA and the Department of Justice.

For more information contact Cindy Drucker or Dave Park, NESCAUM, (617) 367-8540.

Source: NESCAUM