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Draft U.S. Environmental Protection Agency hazardous air pollutant regulations for coal-fired utilities are anticipated by March 2011, and the expectation is that very high emission reductions (90% or greater) will be required for mercury control. Activated carbon injection (ACI) is expected to be a key tool for achieving these reductions; however, typical performance data with ACI suggest that in-flight mercury capture becomes exponentially more difficult at high reduction levels. Because of this decreasing sensitivity of mercury capture to carbon injection rate, ACI parameters will need to be optimized in order to consistently achieve high reduction targets. Unfortunately, optimization data may not exist for a number of plants since existing site-specific data may have been collected with outdated mercury capture targets in mind, and the ultimate capture potential or its sensitivity to plant operations was not thoroughly examined. To add to this dilemma, optimizing the maximum mercury reduction with ACI is not a trivial matter since there are number of potential bottlenecks that can limit overall capture. These restrictions range from insufficient sorbent distribution and contact time in the flue gas, to one of many kinetic limitations that arise under the conditions encountered in flue gas. This presentation will discuss the common mechanisms that limit mercury capture with ACI, as identified through fundamental study of mercury–carbon interactions and analysis of pilot and field data. Recognizing the typical trends with mercury capture can assist in the selection of ACI parameters that are most likely to achieve high reductions that may be mandated in the near future.
Revision Date: 5/11/2011
Tags: 221112 - Fossil Fuel 化石燃料, Energy & Environmental Research Center, Activated Carbon Injection System, Air Quality, USA
Jon Miller, Technical Support Engineer at Albemarle Corporation, explained that M-PACT is an equipment package to inject activated carbon at much lower cost than a custom design. The first M-PACT unit was sold in 2007 and is providing reliable 90 percent mercury reduction. There are a number of components in the larger systems which are critical. One is the choice of blower for the pneumatic conveying. A regenerative blower is less expensive but has a lower pressure output and is less tolerant of dirty environments. A Roots type PD blower is more expensive but capable of higher pressures and will tolerate some dust.
Revision Date: 11/19/2010
Tags: 221112 - Fossil Fuel 化石燃料, Albemarle, Activated Carbon, Activated Carbon Injection System, Blower, MACT, Industrial Boiler