Engine makers: non-road diesel particulate filter mandate problematic before 2010; ULSD fuel becomes essential

Diesel Fuel News, Sept 30, 2002 by Jack Peckham

Engine Manufacturers Association (EMA) and Euromot (Europe's EMA) warn in a new report that governments should avoid universal mandate of diesel particulate filters (DPFs) on non-road mobile machinery prior to 2010, and must require a 10-ppm ultra-low sulfur diesel (ULSD) for DPF schemes.

Citing numerous test programs on a wide variety of non-road equipment in both Europe and the U.S., the engine makers contend that years of research & development (R&D) will be required for lower-cost, highly reliable technologies.

This R&D will focus on sophisticated engine management, fuel burners, and catalyzed DPF systems, all running on ULSD to ensure successful regeneration of non-road diesel DPFs on scores of engine sizes and applications, they say.

Such systems must be smartly integrated for original equipment manufacturer (OEM) machines, in order to avoid operator problems or deliberate DPF disconnect. New-system cost also must not be so high as to discourage turnover of old, "dirty" equipment with new, ultra-clean diesel equipment, the engine makers warn.

Many non-road machine duty cycles suffer from low average exhaust temperatures, making DPF soot regen especially difficult compared to highway cycles.

According to the EMA/Euromot report, the "ideal" system that seems universally applicable to non-road DPF regen is a "full-flow burner" that not only raises exhaust temps high enough for soot oxidation, but also avoids unwanted nitrogen dioxides ([NO.sub.2]) emissions from catalyzed DPFs.

This system also would avoid uncontrolled exotherms or excessive backpressure, but it would require sophisticated controls to ensure high burner power at high engine speed/low load, and low/no burner power at full engine load. "Fast changes between these extremes can occur and require a corresponding fast burner control," the report warns.

More R&D will be required for sophisticated DPF control units capable of differentiating between backpressure caused by soot and what's caused by lube/fuel additive ash, the report points out.

Some new "smart" scheme also must be developed to alert equipment operators of the need to clean-out the DPF ash, in advance of backpressure-caused engine damage.

Some types of equipment that notionally might have "high-enough" average exhaust temps for a "passive" DPF nevertheless sometimes cause DPF failures, the report shows. So, engine makers must engineer engine/DPF systems for these anomalies, as well as "worst case" scenarios such as extended idling in Sweden or Minnesota in January.

"Smart" design also will have to cover extreme shock applications (like bulldozers) and extreme dirt/dust (construction, agriculture), as well as ensure equipment operator visibility.

Smaller and low-sales-volume equipment also will suffer relatively high DPF system costs, the study shows. Result: Engine-plus-DPF could double the cost of some larger baseline engines, or even triple the cost of some small engines.

* Swiss Retrofits: OEM Input Lacking

Meantime, Switzerland's program mandating DPF retrofits on all diesel construction equipment has proven the need for much more engine maker involvement in DPF R&D, rather than putting the entire burden on equipment operators and government regulators, the study finds.

While Europe's pioneering "VERT" DPF program has led to a list of tested-and-approved DPF technology options, and an applications-based selection criteria scheme, not all the field experience has been happy, the report says.

"Retrofit programs [in Switzerland] are suffering from a lack of responsibility and insufficient involvement of the engine and machine manufacturers," the report found.

* Costs Higher Than Expected

DPF costs are higher than initially expected, in the range of $9,000 for 70 kW engines and $25,000 for 500 kW engines.

While DPF makers have claimed life expectancy of 4,000 to 6,000 hours, some severe, high-vibration operations can slash DPF life to 1,000 hours or less, triggering filter replacements that cost about $3,000 on some machines.

"In general, [construction] contractors are unhappy with the technical assistance and expertise provided by government and suppliers of equipment and PM filters," the report says. A key factor is choosing the right filter for an application, "from reputable firms with adequate field testing to ensure performance," the report warns.