NO_x reduction using amine reclaimer wastes (ARW) generated in post combustion CO₂ capture

Amine reclaimer wastes (ARW) generated in CO2 capture processes demand suitable disposal means. Such wastes contain remaining amine, NH3 and other degradation compounds. This study investigated the potential of using ARW as a NOx reducing agent, under laboratory conditions in a flow reactor. A simulated flue gas containing about 500 ppm of NO and 5% O2 was injected with liquid ARW under different stoichiometric ratios (TN/NO – total N to nitric oxide ratio) and temperatures.

The ARW was obtained from a distillation monoethanolamine reclaimer in an industrial CO2 capture facility with a coal fired boiler. The results indicate that ARW has a significant NOx reduction potential when injected with TN/NO ratios in excess of 1. The optimum temperature is close to 950 ◦C, where 40% reduction in NOx is recorded with a TN/NO ratio of 1.6.

Increasing TN/NO to 8.5 resulted in a 96% reduction. At low TN/NO ratios (<1.6), the NOx reduction potential of ARW is comparable to that of monoethanolamine, but lower than that of NH3. Nevertheless, the fact that ARW is a waste product, together with its demonstrated NOx reduction capability and its calorific value contribution, makes it attractive as an additive to combustion processes, including cement industry kilns.