PARAMETRIC EMISSION MONITORING SYSTEM OF DRY-LOW NOX NATURAL GAS FIRED TURBINES
The strict emission regulations of gas turbines require not only reduction of the emissions level but also continuous monitoring of the in-stack exhaust emissions. This on-line monitoring system ensures continuous compliance with the regulatory limits. Over the past years, the traditional Continuous Emission Monitoring System (CEMS) has been used to directly measure the exhaust emissions. Due to the cost and complexity of the CEMS, the Parametric Emission Monitoring System (PEMS) arises as a low-cost reliable alternative of the CEMS. PEMS calculates the emissions utilizing simple easily measured operating parameters such as ambient conditions and turbine speed. According to the authors literature review, generic PEMS which is applicable to all types of gas turbine combustors is not yet available. This paper presents the modeling study of a gas turbine combustor based on first engineering principles to fully characterize the nitrogen oxides (NOx) and carbon monoxide emissions (CO). The model is mainly focused on the emissions from a widely used lean-premixed, dry-low NOx combustor. The combustor is divided into several zones where each zone can be considered as a plug-flow reactor. Each of these zones is assumed to have a uniform pressure, temperature and perfect mixing between combustion spices. The temperature of each zone is calculated using the mass and energy balance along with the heat transfer through the combustor liner. The emissions are calculated using well-known pollutant reaction schemes such as the Zeldovich mechanism in addition to other well-established semi-empirical correlations.