A linear VGA nozzle -- A versatile tool for coal utilization[Variable Gas Atomization]

The increasing worldwide recognition of the need to control emissions of the harmful flue gas constituents from the combustion of coal and other fossil fuels is resulting in a considerable demand for lower cost air pollution control equipment. The need is felt not only in the US, with its large existing capacity of older power plants equipped to burn high-sulfur coal, and in Europe, but in third world countries where new lower-capital-cost power plants are needed to meet the growth in energy consumption. Among the alternatives to wet scrubbing that are under development, dry sorbent injection (DSI) appears to provide the lowest capital cost. It has not been accepted to date because of the high operating cost that results from a low SO{sub 2} capture efficiency (50%) plus a low sorbent utilization and resulting high wastage (50%) with customary hydrated lime. A combination of two process changes are now being undertaken to achieve not only a significant increase in efficiency and sorbent utilization (70--80%, and higher), but also an attractive reduction in the parasitic power consumption required for sorbent injection and in the associated high capital investment in air compressing equipment. One change involves the use of the high-surface-area hydratedmore » lime sorbent commercially developed and utilized in Europe in combination with the addition of sodium salts. The other change involves the use of the linear VGA nozzle for combining the water atomization and the injection of the dry sorbent in the same nozzle-lance. By producing a more rapid and complete intermixing of flue gas, sorbent and finely atomized water, the adsorption and reaction of SO{sub 2} is increased, and a higher sorbent utilization is obtained. The dual-function (combining DSI with fine atomization of water) linear VGA nozzle-lance is currently under test in Turkey for ultra-high-sulfur fuel service.« less