Water and steam injection in cogeneration system

Abstract

A control system for a cogeneration plant measures the flow of steam exceeding the requirements of the steam-using process. Water is injected into the combustion zone of a combustor of the gas turbine portion of the cogeneration system to provide a predetermined reduction in NOx products. The excess steam is added to the output of the compressor portion of the gas turbine to augment the gas turbine power output due to the augmented mass flow. The control system reduces the water injection in proportion to the steam flow to maintain the total water flow to the combustion zone at a level which maintains the preferred level of NOx reduction. In a second embodiment, the excess steam is first injected into the combustion zone with a one-for-one equivalent reduction in water injection. When the excess steam exceeds the amount required for NOx reduction, the excess is added to the output of the air compressor for power augmentation. As the power augmentation steam is added a proportionate reduction is made in the NOx reduction steam to account for the fact that a fraction of the output of the air compressor passes through the combustion zone.

Dependencies are inferred from the claim text.