Precision Turbine Flow Meters Assist in Lower NOx on Gas Turbines

Turbine Flow Meters Assist in Lower NOx

As smaller power sources, gas turbine generators are cost-effective solutions. Packaged as systems, they offer flexibility and simplicity with a capacity of 20 MW to over 1000 MW. The gas turbine engine is proven and reliable technology that allows for relatively rapid installation of a complete package almost anywhere.

Regulatory agencies and manufacturers are examining emissions standards that further restrict the release of pollutants into the atmosphere and are increasingly developing systems to meet ever-tighter standards. In gas turbines, nitrogen oxides (NOx) resulting from the combustion of fuel and air, and any nitrogen component, are the primary pollutants produced. The turbine's firing temperature and the fuel used heavily influence a standard gas turbine's NOx emission.

One method of NOx reduction is water injection, used since the 1970s. Systems inject water vapor directly into the combustor of a  gas turbine, reducing the flame's temperature, which decreases NOx emissions in turn.

By injecting demineralized water directly with the fuel (natural gas, fuel oil, etc.), it achieves a reduction of turbine firing temperature, directly correlating to a decrease in NOx emissions. Demineralized water minimizes scaling and build-up in the nozzles and the combustion chamber. As the generator's load increases, additional water maintains 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 to control the feedwater valve position while monitoring the firing temperature. This application requires a very accurate flow meter for a precise control scheme.

The Flow Technology FT Series turbine meter with the LA-5 linearizing electronics and an extended range calibration to give a turndown of 100:1 over the flow range fits the bill.  Available with either meter-mounted or remote-mounted electronics and high temperature amplified pickoffs that eliminate noise generated by the floating (non-grounded) electrical system of the turbine generator. Additionally, the FT Series turbine meter can be placed inside the generator room due to its compact size and durability under extreme conditions. 

Hile Controls of Alabama