Low Nox turbine

An experimental gas turbine simulator equipped with an ultralow-emissions combustion technology called LSI has been tested successfully using pure hydrogen as a fuel.

The LSI (low-swirl injector) technology, developed by Robert Cheng of the US Department of Energy’s Lawrence Berkeley National Laboratory, recently won a 2007 R&D 100 award from R&D magazine as one of the top 100 new technologies of the year.

The low swirl injector itself is a mechanically simple device with no moving parts that imparts a mild spin to the gaseous fuel and air mixture that causes the mixture to spread out. The flame is stabilised within the spreading flow just beyond the exit of the burner. Not only is the flame stable, but it also burns at a lower temperature than that of conventional burners.

The production of nitrogen oxides is highly temperature-dependent, and the lower temperature of the flame reduces emissions of nitrogen oxides to very low levels. Tests at Berkeley Lab and Solar Turbines showed that the burners with the LSI emit 2 parts per million of NOx (corrected to 15% oxygen), more than five times times less than conventional burners.

A more significant benefit of the LSI technology is its ability to burn a variety of different fuels from natural gas to hydrogen and the relative ease to incorporate it into current gas turbine design — extensive redesign of the turbine is not needed. The LSI is being designed as a drop-in component for gas-burning turbine power plants.

Robert Cheng views an LSI flame. He is touching the burner, demonstrating that it stays cool because the flame is completely lifted from its body. 

The Department of Energy’s Office of Electricity Delivery and Energy Reliability initially funded the development of the LSI for use in industrial gas turbines for on-site (i.e. distributed) electricity production. The purpose of the research was to develop a natural gas-burning turbine using the LSI’s ability to substantially reduce NOx emissions.

Cheng, Berkeley Lab colleague David Littlejohn, and Kenneth Smith and Wazeem Nazeer from Solar Turbines of San Diego adapted the low-swirl injector technology to a Taurus 70 gas turbine that produces about 7MW of electricity. It is continuing the LSI development for carbon-neutral renewable fuels available from landfills and other industrial processes such as petroleum refining and waste treatments.

The Department of Energy’s Office of Fossil Energy is funding another project in which the LSI is being tested for its ability to burn syngas (a mixture of hydrogen and carbon monoxide) and hydrogen fuels in an advanced IGCC plant (Integrated Gasification Combined Cycle) called FutureGen, which is planned to be the world’s first near-zero-emissions coal power plant.

The intention of the FutureGen plant is to produce hydrogen from gasification of coal and sequester the carbon dioxide generated by the process. The LSI is one of several combustion technologies being evaluated for use in the 200+MW hydrogen turbine that is a key component of the FutureGen plant.

The technology is available for license for gas turbines and certain other fields of use.

For information, go to http://www.lbl.gov/Tech-Transfer/techs/lbnl0916.html.