Electrically-heated combustion catalyst structure and method for

Abstract

This invention relates to an electrically-heated catalyst (EHC) and a start-up method of a gas turbine engine for combusting a hydrocarbonaceous fuel/oxygen-containing gas mixture using this electrically-heated catalyst. The catalytic structure is electrically heated to a predetermined temperature prior to start up of the turbine so as to reduce emissions during the start-up of the system. The EHC unit is a stacked or spirally wound layering of flat and corrugated thin metal foils which forms a plurality of axially-extending, longitudinal channels. The channels are preferably coated on one surface with a catalytic material, leaving the other surface free from the reaction to act as a heat sink, making the design an IHE (integral heat exchange) catalytic unit. The preferred embodiment of the EHC has electrodes outside of the fuel/oxygen-containing mixture stream, and uses electrical power having a predetermined voltage in the range of 100 to 200 volts to heat the unit. A method for using the EHC in the start-up of a gas turbine is also disclosed wherein an electrical power is applied to heat the EHC a predetermined temperature prior to the fuel/oxygen-containing mixture being introduced and may be left on for a certain period of time after the introduction of the fuel/oxygen-containing mixture. The EHC may be maintained at the desired predetermined temperature by modulating the applied voltage. The electrical power is terminated when any one of several conditions are met including when the heat of the catalytic reaction is sufficient to maintain the catalyst at its steady-state condition or when a certain period of time has elapsed.