Patent ID: 7950217

Claim:
A method for generating heat energy, comprising: a) operating a cogeneration system in a first mode in which a gas turbine engine is operated to produce energy, wherein combustion products from the gas turbine engine are exhausted into a main exhaust duct and into the atmosphere; and b) operating the cogeneration system in a second mode in which the gas turbine engine disabled and a steam generation system operates to generate energy, wherein the operation in the second mode comprises: i) flowing a combustible mixture into an ignition unit in order to combust the combustible mixture and produce exhaust gas which is exhausted at the main exhaust duct; ii) introducing a recirculated portion of the exhaust gas at a location of the steam generation system upstream of the ignition unit; and iii) introducing an oxygen-enriched gas at a location of the steam generation system proximate to the ignition unit, wherein the oxygen-enriched gas has an oxygen concentration greater than 21%, wherein during operation of the cogeneration system in the first mode, the combustion products are not recycled for combustion thereof.