Nett retrofit urea-SCR system receives EPA verification

20 July 2010

US Environmental Protection Agency (EPA) has verified the Nett Technologies BlueMax 100 urea-SCR system for mobile nonroad diesel engines. It is the first verification for a retrofit SCR system granted under the EPA ETV program.

The SCR system utilizes an Fe-zeolite SCR catalyst coated on a cordierite substrate followed by an ammonia slip catalyst. Other components of the system include a urea tank, a urea injection system and an electronic control unit. The monitoring and notification system, based on a urea level and other sensors, includes a mechanism to interrupt engine restart in the event of an empty urea tank.

The verification testing, conducted at the Southwest Research Institute, included emission testing as well as tests of the monitoring and notification functionality of two SCR systems: a fresh (‘degreened’) system and an aged system that accumulated over 1100 hours in the field, installed on a wheel loader powered by a Caterpillar 3406 engine.

The system reduced NOx by 70/68% (degreened/aged) over the steady state 8-mode cycle, and by 66/65% over the NRTC cycle. A PM emission reduction of 26/30% (degreened/aged) was measured over NRTC, but somewhat inconsistent PM emission results—a 12% reduction with degreened system and a 12% increase with aged system—were measured over the 8-mode test. CO emissions were reduced by 87-94% and HC by 99-100%.

This verification represents the first-ever EPA/ETV verification for an SCR-based diesel NOx reduction system. No urea-SCR retrofit system has been verified in California, but a verification was granted in 2005 for an ammonia-based SCR system.

The development and verification of the Nett BlueMax 100 SCR system has been in part supported by a grant from the Texas Environmental Research Consortium (TERC).

Source: US EPA