The scientists compensated for this by injecting the dry sorbent further away from the firing point in a power plant, where temperatures can exceed 1,000 degrees Celsius.
"At 400 to 600 degrees Celsius, the rate of capture should be more than sufficient to effectively remove the selenium from the gas environment," Mahuli said.
More work is needed to discover the best way to stabilize and dispose of fly ash and the lime sorbent, which will contain the selenium, Fan said. There are currently no regulations regarding selenium disposal. The researchers are also trying to find out how much it would cost to retro-fit a plant for this technology.
"It's unclear just how strict the EPA regulations on selenium are going to be," Fan said. "Some plants may find it easier to install a very expensive wet scrubber to remove all of the harmful byproducts from flue gas and fly ash."
But dry sorbent injection technology could be more cost efficient for the removal of selenium, and possibly arsenic. Another advantage to the technology is the abundance of the raw material limestone, especially in the Midwest, Fan said.
The study was co-authored by Rajeev Agnihotri, a doctoral student in chemical engineering, and Abhijit Ghosh-Dastidar, a former post-doctoral researcher, both from OhioState. The work, which was published in a recent issue of the journal Environmental Science and Technology, was supported by the OhioCoal Development Office, a collaborative effort between OhioState and four other Ohio universities.
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Contact: Liang-Shih Fan
Fan.1@osu.edu
614-292-7907
Ohio State University
11-Jul-1996