SPECIFICATION, DEVELOPMENT, AND TESTING OF THE FT8-2 DRY LOW NOX CONTROL-SYSTEM

This paper describes the specification, development, and testing of th e FT8-2 Dry Low NOx control system, and how the lean burn process requ ires an integration of the control system and combustion hardware. The FT8-2 digital fuel control system was developed to achieve the precis e multizone fuel metering of both gas ans liquid fuels, the calculatio n of combustor air flow necessary to achieve Dry Low NOx and the tradi tional governing/limiting control loops necessary for safe, stable eng ine operation. The system design goals were accomplished by the concur rent development of software-based fuel metering algorithms and fuel m etering hardware. The fuel metering hardware utilizes an all-electroni c valve positioner, employing a combination of feedback and software t o achieve closed-loop control of actual fuel flow. Extensive testing u nder actual gas flow conditions and closed-loop bench testing using a real time engine model and fuel system model was conducted to prove sy stem operation and develop system transient response prior to installa tion on the test engine. The setup and results of the flow testing and closed-loop testing are described. The paper describes the control sc heme used to apportion the gas fuel between combustion zones and how e xternal conditions such as apportion the gas fuel between combustion z ones and how external conditions such as ambient temperature and fuel gas composition affect the apportionment. The paper concludes with a d escription of the control system installation in the engine test cell and a review of engine test results.