Combustion modification control technology

Relationship of Pollutant Chemistry to Existing Combustion Modification Control Technology... 

There are several approaches available to a utility to construct a boiler that will meet New Source Performance Standards. These approaches can be classified according to the position in the combustion system at which pollutant control technology is applied. Precombustion control involves removal of sulfur, nitrogen, and ash compounds from the fuel before it is burned. For coal combustion this approach involves the application of coal-cleaning technology. Combustion control relies on modifications to the combustion process itself or the addition of material to the combustion process to reduce pollutant formation or capture the pollutants formed in the combustion chamber. Examples of combustion control include staged combustion, boiler limestone injection, and fluidized-bed combustion with limestone addition. Post-combustion control involves removal of pollutants after they have been formed but before they are released into the atmosphere. Traditionally, flue gas desulfurization has meant the application of postcombustion control either alone or in conjunction with another... 

A very small fraction of the nitrogen in the coal and/or air is converted to gaseous NO, during combustion. These are pollutants that must also be removed from the flue gas or controlled bv combustion modification, but that technology is not within the scope of this case study. 

As Table I indicates, almost half of the total national NOa emissions result from stationary fuel combustion. In principle, NOa emissions from fossil fuel-combustion systems can be reduced by three methods fuel cleaning (removal of the fuel nitrogen), combustion modification, and flue gas treatment. Combustion modification appears to be by far the easiest and most economical of the three. Therefore, EPA has assigned to the Control Systems Divisions, Combustion Research Section (CRS) the responsibility for assisting industry in developing technology to re-... 

Technologies developed for controlling the emissions of nitrogen oxides can be classified in two groups (i) those consisting of combustion modifications to reduce the formation of NO (primary or in-furnace measures) and (ii) those consisting of effluent treatments to remove NO (secondary measures). 

For some combustion sources, RACT, BACT, and LAER have and will require add-on controls or combustion modifications to limit emissions. These add-on control technologies are relatively new and can represent high capital and maintenance costs, especially for industrial boilers and heaters. The low-cost combustion-modification techniques involve burner modifications with total capital cost under 50,000 per boiler. 

As the requirements for future military combustors become increasingly demanding, an advanced combustion control system that can effectively shorten the combustor development time and improve the combustor performance will be an important technological asset to our military. Active combustion control (ACC) is an attractive idea because it relies on proper timing of fuel injection rather than spatial changes of flow field as required in passive approaches. Since timing adjustment is simpler than potential geometry modifications associated... 

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