ENVIRONMENTAL ENGINEERING
Corn-based carbon adsorbent tested at Illinois power plant

James E. Kloeppel, Physical Sciences Editor
(217) 244-1073; kloeppel@uiuc.edu

9/1/2001

CHAMPAIGN, Ill. — A successful full-scale test of the carbon-injection process for removing mercury emissions from coal-fired power plants took place July 30-Aug. 12 at the University of Illinois Abbott Power Plant. The technology demonstration tested a commercial activated carbon and a corn-derived activated carbon developed by researchers at the Illinois State Geological Survey and the UI.

"This full-scale test capped a five-year collaborative effort to develop low-cost adsorbents for the removal of mercury," said Massoud Rostam-Abadi, a chemical engineer and the head of energy and environmental engineering for the ISGS. "The test also marked the first time the carbon-injection technology was applied to high-sulfur Illinois coal flue gas."

In previous work, the UI and Survey scientists tested the suitability of activated carbons derived from sources such as used tires and pistachio shells. But those tests were conducted in the laboratory.

"Earlier this year, we worked with engineers from URS Radian (in Austin, Texas) to look at the effectiveness of corn-based activated carbons for removing both elemental mercury and mercuric chloride from simulated coal combustion flue gases," Rostam-Abadi said. "Our initial tests indicated that activated-carbon adsorbents made from corn could work as well as or better than current commercial products, and might even be cheaper to produce."

Then, in May, the researchers screened 13 of their experimental adsorbents using actual flue gas from the Abbott Power Plant. Based on the results of those bench-scale tests, two activated carbons – a corn-based material and a commercial product – were selected for full-scale testing.

"In the carbon-injection process, adsorbent particles are typically in contact with the flue gas for less than a few seconds," said Mark Rood, a UI professor of civil and environmental engineering. "Therefore, the most desirable adsorbent would have high reactivity and low cost."

A team of engineers from Apogee Scientific in Denver and URS worked with Survey and UI engineers to conduct the full-scale tests at Abbott Power Plant – a 30-megawatt facility that burns high-sulfur Illinois coal. First, parametric testing and optimization were performed with the commercial carbon. Those results were then compared with results obtained with the corn-derived carbon.

"One of the unique aspects of our program is going from laboratory development, to pilot-scale testing and then to full-scale testing," Rostam-Abadi said. "Few universities have that capability."

The scientists presented their latest findings at an Air & Waste Management Association specialty conference on mercury emissions, held in Chicago Aug. 20-23.

In addition to Rostam-Abadi and Rood, collaborators on the project include Survey chemical engineer Scott Chen and UI graduate students Hsing-Cheng Hsi and Christopher Lehmann. The Electric Power Research Institute, Illinois Clean Coal Institute, Illinois Office of Solid Waste Research and Illinois Corn Marketing Board supported the research.