Gas Turbine Data

The primary data to be reviewed comes from two gas turbines operating in parallel. These gas turbines generate power to meet local demand, include primary fuel firing, a pilot gas flow and duct burner natural gas to produce energy. A major operating constraint is permit allowed emission levels, which are managed by a SCR (selective catalytic reduction of NOx) with ammonia injection. To investigate the influence of operating conditions and environment on emissions or turbine efficiency data has been gathered, but it is also important to note that NOx is measured in front of the SCR (inlet NOx), which is generated by the different combustion sources based on air and firing conditions. NOx after the SCR (Stack NOx) is primarily dependent on SCR operating conditions along with the amount of NOx entering the catalytic reduction unit. Best practice is to investigate these two processes of evaluating what causes NOx levels separately. Secondly we have two independent turbines, Unit 1 and Unit 2. We can anticipate that efficiencies and NOx influences are independent, but may also show similar interactions. Finally you may consider how NOx is generated in a combustion process. Natural gas (CH4) does not have any Nitrogen content, so the generation of NOx in combustion comes from the oxidation of combustion air Nitrogen. Most people assume this is highly correlated (and nonlinear) with flame temperature although flame temperature is a very hard and therefore rarely measured value. Efficiency (power generated per amount gas consumed) may be a function of load, Oxygen levels (the amount of extra air brought in with the amount required for complete combustion) and other areas of possible inefficiencies within the turbine.

It is best practice as part of a data exploration process to start by gathering information on what is known or suspected about what is being evaluated. Primarily we want a model that extends from current knowledge so having this in mind lets us pull in what is known along with what are suspected influences on our investigated business objectives.