Non-Catalytic NO{sub}x Removal from Gas Turbine Exhaust with Cyanuric Acid in a Recirculating Reactor; Small Scale Evaluation and Industrial Application

摘要

A novel SNC technique to remove oxides of nitrogen (NO{sub}x) from stationary gas turbine exhaust has been investigated and applied. The technique employs the use of cyanuric acid (CYA), a nontoxic, dry powder, combined with the injection of auxiliary turbine fuel and recirculation. During the initial investigation, exhaust, generated by a 150 kW gas turbine, was treated in an insulated recirculation reactor, with a mean residence time of 0.65 to 0.71 seconds and a pressure drop of 660 Pa. In the reactor, autoignition of injected auxiliary gas turbine fuel raises the flue gas temperature to between 700 and 800°C. CYA slurry is injected. Temperature rise and NO{sub}x reduction occur simultaneously. At all temperatures, significant NO{sub}x reduction from initial concentrations of 106 to 124 ppm to as low as 18 ppm at 15% O{sub}2 have been observed. Load following has been achieved. The process generates N{sub}2O emissions, which vary from 45 to 163 ppm, increasing with increasing CYA/NO{sub}x ratio. The performance of CYA ((HNCO){sub}3) is compared to that of ammonia (NH{sub}3) and urea ((NH{sub}2){sub}2CO). A numerical model, which combines a detailed chemical kinetic mechanism with recirculation, has been developed. The model captures all observed trends well and is an invaluable guide to improved understanding of the interactive NO{sub}x removal process. The process was then successfully scaled up and applied to a variety of industrial 3.7 MW gas turbines and similarly significant NO{sub}x reduction has been achieved.