How does flue gas desulfurization work

Search A-Z Suche nach. Flue gas desulphurisation system In a f lue g as d esulphurisation system FGD , sulphur compounds are removed from the exhaust emissions of fossil-fuelled power stations. See Fig. The flue gas then flows to a particulate control device e. Both dry injection and spray dryers yield a dry final product, collected in particulate control devices.

At electric generating plants, dry scrubbing is used primarily for low-sulfur fuels. At municipal waste-to-energy plants, dry scrubbing is used for removal of SO 2 and HCl. Dry scrubbing is used at other industrial facilities for HCl control.

Dry scrubbing methods have improved significantly in recent years, resulting in excellent removal efficiencies. In wet lime scrubbing, lime is added to water and the resulting slurry is sprayed into a flue gas scrubber.

In a typical system, the gas to be cleaned enters the bottom of a cylinder-like tower and flows upward through a shower of lime slurry. The sulfur dioxide is absorbed into the spray and then precipitated as wet calcium sulfite. The sulfite can be converted to gypsum, a salable by-product. Wet scrubbing treats high-sulfur fuels and some low-sulfur fuels where high-efficiency sulfur dioxide removal is required.

The byproduct is then eliminated through particulate control equipment. Water can be injected further downstream in the emission flow to increase efficiency. Dry scrubbers are less expensive to install, require less space, and have simpler byproduct disposal. However, they also have the lowest efficiency at only 50 to 60 percent for calcium injections, and up to 80 percent for sodium injections.

Rubber lining significantly lowers the cost to operate flue gas desulfurization systems. The water required to run each system, and the quantity of wastewater produced, can be the single largest expense. Rubber lining reduces that expense by reducing the amount of water required to achieve maximum efficiency. Flue-gas desulfurization plant.

Fossil fuel plants power chemical and oil refineries, as well as those facilities that produce cement, paper, glass, steel, iron, copper, and other metals. The SO 2 gases emitted as a result of that process are a primary contributor to acid rain and has long been regulated by every industrialized nation in the world due to their harmful effects on human health and the environment. In the U. Flue-gas desulfurization was an important development to meet environmental challenges.

The process of FGD is designed to absorb the sulfur dioxide in the flue gas before it is released. This is accomplished through either a wet or a dry process. In the process of dry scrubbing injection systems, lime is used as a reagent to react and remove gaseous pollutants. There are two common dry methods, the dry injection system and spray drying systems. Each process injects lime into flue gas to remove SO 2.