CAA-90 is here

Industry now must conform to the stringent and costly Clean Air Act amendments of 1990. It no longer matters that this political bill, itself a threat to the economy in certain respects, apparently ignored responsible scientific findings, particularly those of the National Acid Precipitation Assessment Program (NAPAP). It no longer matters that the bill appeared to ignore the gains under the existing CAA. These gains allowed power plants to boost coal consumption from 570 million tons/yr to 766 million tons/yr during the 1980s, and yet reduce total sulfur dioxide emissions by roughly two million tons. What does matter is that research and development continues to prove new technologies and improve existing pollution control systems. It remains to be seen whether CAA-90's demands and costs will interfere with the logical progress of dependable technologies. In any case, many power plant staffs now must seek extra help from applied researchers and engineers to find the best and most affordable technologies for meeting the new regulatory demands and deadlines. Some research, underway for years, may hold promise of one preferred option; that of retrofitting improved pollution controls to operating power plant systems. This paper notes that research on certain integrated processes could lead to relatively low- cost NOx control retrofits of wet and dry scrubbing technologies. The use of metal chelates in wet scrubber liquors for NO removal is progressing to the pilot scale phase and has the potential for 50-70% NOx removal along with 90 + % SO2 removal. Addition of sodium hydroxide to a lime slurry for integrated NOx removal in spray dryer systems was demonstrated at a 20-MW industrial boiler and is ready for commercial-scale tests. Depending on the coal being burned, NOx removals of 35%-50% are potentially achievable along with 70%-90% SO2 removal