Title:Advanced Fuel to Air Ratio Control for reciprocating legacy natural gas EnginesAuthor(s):Martin RanzmaierAbstract:The governmental regulations concerning emissions of fossil fuel powered engines are more and more strengthened. New laws are focusing especially on nitrogen oxide and nitrogen dioxide emissions (NOx). Not only car engines are affected by strong emission restrictions, but also industrial engines. Several techniques are known to reduce the NOx emissions, especially an advanced fuel to air ratio Phi control is known as major step towards further emission reduction. The possibility to reduce the NOx emissions is investigated for legacy reciprocating natural gas powered engines. This kind of engine is used on pipeline pump stations. The typical control on such pipeline engines consists of nested SISO PID loops. The system has naturally a MIMO structure. A MIMO control can use the information about the coupling to improve the overall control performance. Two MIMO model based controller, which inherently take into account the couplings, are designed. By simulation, the control performance was compared with the SISO control performance. The most promising approach a model predictive control (MPC) was implemented on the real engine. Focusing on the squared Phi deviation over 80 % reductions can be achieved.Publishing:5/2008