COMBINED WASTE GAS TREATMENT OF WASTE GAS FLOWS CONTAINING AMMONIA AND NITROGEN OXIDES IN INDUSTRIAL PLANTS

摘要

Process for the combined removal of both ammonia in one or more ammonia-containingwaste gas flows and nitrogen oxides in one or more additional nitrogen oxide-containingwaste gas flows in a combined ammonia/urea synthesis plant according to theselective non-catalytic reduction in a temperature range from 850°C to1100°, by whichnitrogen oxide reduction rates of up to 80% are achieved, or according to theselectivecatalytic reduction in a temperature range from 150°C to 550°C,by which nitrogen oxidereduction rates of up to 99% are achieved, in which the ammonia and thenitrogen oxidesreact with one another to give nitrogen and water, the ammonia-containingwaste gasflow to be treated from a low-pressure absorber and/or an atmospheric absorberof theurea synthesis plant unit being mixed with the nitrogen oxide-containing wastegas flow tobe treated of a flue gas duct of a primary reformer of the ammonia synthesisplant unit ofthe combined ammonia/urea synthesis plant and being submitted to a selectivenon-catalyticreduction or a selective catalytic reduction depending on the temperature ofthemixture and depending on the nitrogen oxide reduction rate to be reached, boththeammonia and the nitrogen oxides of the mixed waste gas flows being depletedsimultaneously during the same process step.