SCR distribution: Building an infrastructure network for diesel exhaust fluid
Mar 1, 2009 12:00 PM
Most of the new diesel engines set for launch in 2010 will have an emission control system that includes selective catalytic reduction (SCR). The SCR systems currently under development use a diesel exhaust fluid containing an engineered grade of urea, a liquid chemical, for meeting the near-zero emission limits required for diesel engines built in 2010 and beyond.
By some estimates, the US trucking industry will consume at least one billion gallons of urea a year within four to five years of the 2010 engine launch. Diesel engines in cars and light trucks also will have SCR emission control systems, which could push total demand for SCR-grade urea well above one billion gallons.
Suppliers of SCR-grade urea are in the process of developing transport requirements and building a distribution network. One such company, looking to serve the SCR urea market in North America, is Terra Environmental Technologies, a urea processor based in Courtright, Ontario, Canada.
“We're developing an integrated supply approach for this highly engineered product,” said Barry Lonsdale, company president. “We have to ensure that we can meet tight quality requirements throughout the distribution process.”
There are two key issues. One is that SCR urea must contain a precise concentration of ammonia when it reaches the customer. The other is the purity of the urea solution must be very high.
“Impurities (greater than 20 parts per million) could cause failure of the emission aftertreatment system,” Lonsdale said. “We're already seeing the effects of non-compliant urea in test fleets.
“One of the biggest concerns we have is that some truck operators will be tempted to use ag-grade urea, which doesn't meet the 2010 diesel engine spec and will kill the catalytic converter. In addition, we know that off-spec foreign imports probably will enter the North American market.”
Terra Environmental Technologies is working with dispensing system manufacturers Gilbarco Veeder-Root and Dresser Wayne on standardized urea dispensing units that would be placed on the diesel fuel islands at truck stops. Dispensing units also might be installed at other customer locations.
Among truck stops, Pilot Travel Centers announced that it plans to be the first to carry diesel exhaust fluid (urea) at the fuel island for SCR-equipped trucks. Initial rollout plans call for availability in bulk dispensing capabilities at locations across the US later this year.
Over a relatively short time, demand for SCR-grade urea will surge in the trucking industry. Heavy-duty truck engine builders that plan to use SCR include Cummins Engine, Detroit Diesel, Mack Trucks, Paccar, and Volvo Trucks North America.
Navistar is the only major North American truck engine builder that has announced it will be using in-cylinder exhaust gas recirculation (EGR) for its 2010 MaxxForce diesel engines.
The amount of diesel exhaust fluid carried on a truck will depend on the fuel capacity. Based on an estimated dosing rate of 3% to 5%, a truck with a 300-gallon fuel supply probably would need a 15-gallon plastic or 304 stainless steel insulated diesel exhaust fluid tank. Drivers would refill the fluid tank every time they refueled the truck.
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