Corn-based carbon adsorbent tested at US power plant

Researchers at the University of Illinois Abbott Power Plant have successfully tested a carbon-injection process for removing mercury emissions from coal-fired power plants.

The technology demonstration, which took place between July 30 and August 12, 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-sulphur 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-sulphur Illinois coal.

First, parametric testing and optimisation were performed with the commercial carbon. Those results were then compared with results obtained with the corn-derived carbon.