A Partial Oxidation Staging Concept for Gas Turbines Using Broadened Specification Fuels

A concept is described for using a very fuel-rich partial oxidation process as the first stage of a two-stage combustion system for onboard processing of broadened specification fuels to improve their combustion characteristics. Results of an initial step in the experimental verification of the concept are presented, where the basic benefits of H₂ enrichment are shown to provide extended lean-combustion limits and permit simultaneous achievement of ultralow levels of NO_x, CO, and HC emissions. The H₂ required to obtain these results is within the range available from a partial oxidation precombustion stage. Operation of a catalytic partial oxidation reactor using a conventional aviation turbine fuel (JP5) and an unconventional fuel (blend of JP5/xylene) is shown to produce a “fuel gas” stream with near-theoretical equilibrium H₂ content. However, a number of design considerations indicate that the precombustion stage should be incorporated as a thermal reaction.