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NOx Emissions In Gas Turbine Generators

APPLICATION NOTE: Turbine Flow Meter Aids Reduced NOx Emissions in Gas Turbine Generators

Gas turbine generators are a costeffective solution for smaller power sources. They provide flexibility and simplicity and are packaged as systems from 20MW to over 1000MW capacity. The gas turbine engine is a proven and reliable technology that allows a complete package to be installed relatively quickly, almost anywhere.

gas turbine generator
Diagram of a gas turbine generator

Regulating agencies are reducing emissions standards which further restrict the release of pollutants into the atmosphere, and manufacturers are increasingly developing systems to meet ever tighter standards. In gas turbines, the primary pollutants produced are the oxides of nitrogen (NOx), which result from combustion of fuel in air as well as any nitrogen component in the fuel. The NOx emission of a standard gas turbine is heavily influenced by the turbine firing temperature and the fuel used.

Water injection systems have been developed that directly inject water vapor into the combustor of a gas turbine for NOx abatement. This is accomplished by reducing the flame temperature, which in turn reduces NOx emissions. It was first used on industrial generators as far back as the 1970s.

Demineralized water is directly injected along with the fuel (natural gas, fuel oil, etc.). The water acts to reduce the turbine firing temperature, which directly correlates to a reduction in NOx emissions. Demineralized water is used to minimize scaling and build-up in the nozzles and the combustion chamber. As the load on the generator increases, additional water is used to maintain the turbine firing temperature low enough to reduce NOx emissions to about 25ppm. The turbine flow meter measures the supply water flow rate to the nozzle injector manifold; this is used to control the feed water valve position while monitoring the firing temperature. A very accurate flow meter is required for this precise control scheme and the FT Series turbine meter is an excellent choice with accuracies within 0.1% of reading.

An FT Series turbine meter is used with the LA-5 linearizing electronics. The meter is supplied with an extended range calibration to give a turndown of 100:1 over the flow range. It can be supplied with either meter-mounted or remote-mounted electronics. High temperature amplified pickoffs are used to eliminate noise generated by the floating (non-grounded) electrical system of the turbine generator. The FT Series turbine meter can be placed inside the generator room due to its compact size and durability under extreme conditions.


Industry: Power Generation

Service: Flow Rate/Total

Fluid: Water


Adding water to the combustion section of a gas turbine generator to lower firing temperature and reduce NOx emissions.


Measure supply water flow rate to help control flame temperature.


FT Series turbine flow meter with high temperature amplified pickoffs and linearizing electronics.

  • Reduced ignition temperature
  • Reduced NOx emissions
  • Optimized flow control

Below are additional resource links for this subject that you may find helpful:

Contact your local VMA field engineer today if you need help or have any additional questions.


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Karen has been a part of Vic Myers Associates team since February 2023. Prior to her position as People and Culture Specialist, she worked in the Science & Technology field as an HR Manager & Project Lead for SAIC and LANL. In the short time with VMA she has learned a lot and looks forward to knowing our business even better in support of all of our employees. She values her church community, her two sons who happen to be engineers, volunteering, and golf. Karen is located in our Albuquerque, NM office.


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Natalie Myers joined Vic Myers Associates in September 2021 and is excited to be part of the team. She received her bachelor’s in business administration from the University of Phoenix and prior to her position as Inside Sales Administration she worked in the Hospitality Industry for over 15 years as a Senior Sales Administrator. In her free time, she enjoys spending time with her husband, daughter, family and friends along with watching sporting events, traveling, hiking and cheering on her daughter in dance and basketball! Natalie is located in our Arizona office.


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