Advances in Coal Blending and Switching is Hot Topic Hour on Thurs., June 10, 2010
Over the last 15 to 20 years, switching coal type or blending different types of coals for combustion at pulverized coal-fired power plants have become very common options employed by utilities to reduce fuel costs, economically achieve SO2 emission limits and improve combustion efficiency. In some cases plants have been modified to use an entirely different coal type than they were originally designed for in order to take advantage of local fuel costs or meet emission limits without significant add on control equipment. However, making the decision to switch coal sources or selecting the correct blend of two or more coals is not an easy task and the most economical coal type or blend that will still achieve other objectives such as maintaining emission limits can change. Low sulfur PRB coal is commonly blended with other higher sulfur coals to meet SO2 emission limits but this can result in de-rating the boiler if it has not been properly designed for combusting a fuel with a high ratio of PRB. Changes in the cost of the raw coal or transportation can have a significant effect on the economics. The coal itself can exhibit variable characteristics and mineral content which will affect the entire operation of the plant from the pulverizer through the combustion process, ash handling and emission control equipment. And the new regulations coming that are expected to include stringent limits on mercury, arsenic, hydrochloric acid and other HAPs emissions, collection and disposal may change the entire decision making landscape.
Methods for blending coals vary from basic manual blending of coals from two or more piles using heavy loaders in the yard, to having several different hoppers feeding a conveyor at preset controlled rates by weight, to using a coal analyzer to dynamically control the blend from different hoppers feeding the pulverizer. Software has also been developed to help predict the performance of different coals and blends and can be used with on-line analyzers to control the boiler fuel feed. Software can also help coal buyers select the best sources based on coal cost, transportation cost and an analysis of the coal composition and mineral content balanced against the operating objectives for combustion efficiency, emissions limits, ash composition and other factors.
The following speakers will help us understand the in and outs of coal blending or switching, the problems to be avoided, technologies and equipment available and under development with their applicability, capabilities, and limitations, costs involved and the benefits that can be attained.
James R. Mooney, Owner-JRM Energy Consulting - Since 1990 the drivers for utilities to modify from their ‘designer’ fuel have been the Clean Air Act amendments of 1990, and the Energy Policy Act of 1992 provisions for open access to transmission to encourage competition leading to deregulation. Opportunity fuels come in many forms best said in the book, Fuels of Opportunity, “The array of opportunity fuels available is as broad and diverse as the ingenuity
of the engineering community”1. This presentation will provide an overview of technology available to assist plants considering changing from over a century of using analysis from a miniscule fraction of the burn to managing opportunity fuels in a veridical, state of the art system where the quality is monitored from arrival at the gate until the blended product exists in the silo for conversion to elections. [1] Fuels of Opportunity, David A. Tillman and N. Stanley Harding, 2004, Elsevier
Kevin Gordon, Applications Engineer, Thermo Scientific Materials & Minerals, Thermo Fisher Scientific will discuss the use of analyzers to effectively blend coal to optimize boiler efficiency in U.S. power plants. A majority of these analyzers are used in bunker feed applications, where the characterization of the coal can be critical for emissions compliance and/or boiler optimization.
Craig Vogel, Project Manager at CH2M Hill
Jeffrey (Jeff) M. Russell, Engineer at MPR Associates, Inc.
To register for the "Hot Topic Hour" on June 10, 2010 at 10 a.m. CDT (Chicago time), click on: http://www.mcilvainecompany.com/brochures/FGDnetoppbroch/Default1.htm
Bob McIlvaine
President
847 784 0012 ext 112
rmcilvaine@mcilvainecompany.com