Flue gas humidification and alkaline sorbent injection for improving vapor phase selenium removal efficiency across wet flue gas desulfurization systems

摘要

A process is provided for removing vapor phase selenium species produced by the combustion of selenium and sulfur-containing fuel of the kind used to generate electric power in conjunction with a flue gas desulfurization process. In one process embodiment the flue gas leaving the combustion system is humidified by the injection of atomized water or a dilute alkaline slurry at a selected location upstream of the flue gas desulfurization system to cool the flue gas from a temperature of about 300° F. to a temperature of about 280° F. so as to enhance the selenium removal efficiency. In another process embodiment the flue gas leaving the combustion system is first humidified to cool the flue gas from a temperature of about 300° F. to a temperature of about 200° F. so as to enhance the selenium removal efficiency, and then an alkaline sorbent material is injected into the humidified flue gas. Selenium species are removed from the flue gas with the particulates in a particulate control device between the combustion system and the flue gas desulfurization system.