Industry Overview: Lime Applications for Flue Gas Desulfurization
Lime is used extensively in the USA for removal of sulfur dioxide (SO2) from flue gases produced by burning of sulfur-containing fossil fuels at power plants and industrial facilities. Lime used for removal of SO2 amounts to 3.16 million tons per year or 16% of the total lime used annually in the USA.
Two major types of lime-based FGD processes are used in the USA:
DRY LIME SCRUBBING -- processes include dry injection, spray dryer or semi-dry processes, and circulating fluid bed processes.
WET LIME SCRUBBING -- processes include the wet high-calcium lime process and the magnesium-enhanced Thiosorbic® lime process, which utilizes 71% of FGD lime, or 2.25 million metric tons per year.
Table 1 shows the major types of lime-based FGD in the USA and the tons of lime used annually by each process.
Benefits of Using Lime
Carmeuse Lime & Stone Technology and Products
New Magnesium -- Enhanced Lime Flue Gas Desulfurization Process:
Carmeuse Lime & Stone has developed a new magnesium-enhanced-lime-based wet flue gas desufurization (FGD) process for control of sulfur dioxide emissions. This process is an improvement upon an older magnesium-enhanced lime process, which has been in use in the USA since 1977. The magnesium-enhanced Thiosorbic® wet lime process utilizes 2.25 million metric tons of lime annually. Since the year 2000, 27% of this lime is utilized in an improved version of the process that produces valuable by-products, gypsum and magnesium hydroxide.
While the by-product produced by the old process (calcium sulfite) had no use and had to be disposed in landfills, gypsum produced by the new process is sold for manufacture of building materials such as wallboard and plaster. The new process can also produce magnesium hydroxide as a byproduct, which has been used successfully for control of sulfuric acid emissions and to eliminate plume opacity.
For a complete report on this technology [Read Document]
