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

A process for removing vapor phase selenium species from flue gas produced by the combustion of a sulfur and selenium-containing fuel in conjunction with a flue gas desulfurization process to produce substantially selenium-free gas for discharge to the atmosphere, wherein said process includes the steps of:

• (a) directing a vapor phase selenium and sulfur oxides-containing flue gas at a first temperature and humidity produced by the combustion of said fuel from a combustion apparatus first to a particulate control apparatus and then to a flue gas desulfurization system;
• (b) humidifying said flue gas leaving said combustion apparatus to increase the humidity of the flue gas to a value above the first humidity and to decrease the temperature of the flue gas to a value below the first temperature, wherein said value below said first temperature is in the range of about 200.degree. to about 280.degree. F.
• (c) injecting an alkaline sorbent material into the humidified flue gas to form solid selenium salts from said vapor phase selenium species in said humidified flue gas;
• and
• (d) removing said solid selenium salts from said flue gas in said particulate control apparatus to produce flue gas for discharge to the atmosphere that is substantially free of vapor phase selenium species.

A process for removing vapor phase selenium species from flue gas produced by the combustion of a selenium-containing fuel to produce substantially selenium-free gas for discharge to the atmosphere, wherein said process includes the steps of:

• (a) directing a vapor phase selenium-containing flue gas at a first temperature and humidity produced by the combustion of said fuel from a combustion apparatus to a particulate control apparatus;
• (b) humidifying said flue gas leaving said combustion apparatus to increase the humidity of the flue gas to a value above the first humidity and to decrease the temperature of the flue gas to a value below the first temperature, wherein said value below said first temperature is in the range of about 200.degree. to about 280.degree. F.;
• (c) injecting an alkaline sorbent material into the humidified flue gas to form solid selenium salts from said vapor phase selenium species in said humidified flue gas;
• and
• (d) removing said solid selenium salts from said flue gas in said particulate control apparatus to produce flue gas for discharge to the atmosphere that is substantially free of vapor phase selenium species.