Technical Paper
Electrically Heated Mixer for Near-Zero Urea Deposit
2024-04-09
2024-01-2377
When used with urea-water solution forming ammonia, Selective Catalytic Reduction (SCR) catalyst is a proven technology for greatly reducing tailpipe emission of nitrogen oxides (NOx) from Diesel engines. However, one major shortcoming of an SCR-based system is forming damaging urea deposits (crystals) in low temperature exhaust operations, especially exacerbated during lower exhaust temperature operations or higher injection rates. Deposits reduce SCR efficiency, damage exhaust components and induce high concentration ammonia slips. We describe here an Electrically Heated Mixer (EHM™) demonstrated on a Diesel engine markedly inhibiting deposit formation in urea SCR systems, including in low (near 200 °C) exhaust temperature operations in both low and high urea injection rates in various, realistic engine operations. Engine test runs were conducted in long durations, 10 to 20 hours each, for a total of nearly 100 hours.