Advanced Rich Burn Control using State of the Art sensors, Actuators, Algorithms and Diagnostics.
Since 1998, Advanced Engine Technologies Corporation (AETC) has worked on the reliable application of Non Selective Catalytic Reduction (NSCR) technology to gaseous fueled engines on behalf of individual clients and the industry via the Pipeline Research Council International (PRCI), often teaming with Hoerbiger. While superficially a 'simple and proven' technology, NSCR control is in fact extremely complex, far more complex than the control of lean burn engines. Using a systems approach, AETC has defined the most common failure modes for each of the components of the NSCR system. In an ongoing effort AETC is testing advanced methods, including advanced sensors, actuators, algorithms and diagnostics to either prevent these system failures or detect them before the system goes out of compliance. When properly installed and calibrated, modern NSCR control systems rarely go out of control. That is, the controller almost always maintains setpoint, but the SYSTEM goes out of compliance. System non-linearities exacerbate the problem. For example, a single setpoint(s) is often inadequate for covering the full range of engine operation, particularly when using non-linear binary (EGO/HEGO) sensors. Utilizing properly spanned linear (UEGO) lambda sensors greatly simplifies the control task. Likewise non-linearities in the mixer and fuel supply system further complicate the control problem and can result in system instabilities. Applying ideal (venturi) mixers along with precision linear fuel controllers greatly simplifies the control problem and improves stability over the range of operation. Linear sensors, mixers and fueling also simplify start and idle operation making it possible to control air/fuel ratio through the complete operating cycle. This greatly reduces the potential for overly rich mixtures to damage the catalyst damage during start, idle and shutdown operation.