WSP01507 - Laserfiche WebLink

Home Browse Search

ro j .......1 Appendix 1. RELATED TECHNOLOGIES (. '--: A number of technologies relating to saline water and coal use are currently being developed. The possibilities offered by these new techniques may enhance the AQUATRAIN Project further, leading to additional benefits and cost savings. Increasing demand for freshwater has made use of saline water more desirable for industrial purposes, such as cooling. Also, regulations requiring zero discharge from powerp1ants have prompted development of economical methods to concentrate cooling water to a small percentage of its original volume. Cooling towers, using saline water delivered by the AQUATRAIN pipeline system, promise to meet both of these objectives. In a powerp1ant cooling tower, a primary cooling loop would contain freshwater while a secondary cooling loop would contain saline water (Figure 5). The loops would be separated by thin plastic sheets to prevent mixing. Heat from the freshwater would be transferred to the saline water, which would become more concentrated through .evaporation. Resultant wastewater of 120,000 milligrams per liter salt concentration would be disposed in evaporation ponds or dry lakes. Deep cleaning techniques for coal (also called washing or benefi- ciation) might be employed in the process of crushing coal for liquid CO? transport in the .pipe1ine . system to eliminate contaminants ~nd produce a high-grade coal product. The results could be higher heat content of the coal, substantially lower costs for emission control equipment, and reduced shipping costs for domestic and export markets. Private industry and government-sponsored projects are developing methods to remove all or part of coal contaminants, such as moisture, ash, and sulfur. The coal product which would result from cleaning might be burned in existing powerp1ants now using expensive oil and gas, or could be burned in present or planned coa1- fired powerp1ants as clean, efficient fuel. Another possibility is the mixing of finely ground coal with either water or oil to produce a fuel for oi1- arid gas-fired powerp1ants. These mixtures, which would have near homogeneous properties, could reduce boiler slagging and fouling and could subsequently improve air quality. Coal that has not been cleaned could fuel powerp1ants without increasing pollution through fluidized-bed combustion. Several fluidized-bed designs are now available or under development for burning any grade of unwashed, crushed coal. In general, all fluidized-bed combustors generate steam from coal via a heat exchanger. In a fluidized-bed system (Figure 6), a mix of crushed coal and limestone (or dolomite) is constantly agitated from below by pressurized airjets. The mix responds in the manner of a boiling liquid, heBce the term "fluidized". The ignited mix burns at 1500 to 1700 F -- one-half the temperature 33