8. Corrosion or plugging, which are characteristics of wet scrubbers, are eliminated because the system does not recirculate a slurry and, therefore, PH control is not a factor of operation. We are concerned, however, that the use and further improvement of this technology will be severely restricted by EPA's draft proposal of the New Source Performance Standards at 85-90% SO2 removal and an emission limitation ranging between 0.2 and 1.2 lbs. SO2 per million BTU. The system clearly meets the 1.2 lbs. SO 502 limit. But this is a "once through" system. Any Alkali which does not react with the SO2 on its way through the system is dried out and discharged with the dry waste product; it is not recycled to the scrubber as in a conventional slurry scrubber. Some excess lime is required in any case, but the amount of excess needed to achieve 90% removal is so high that the process may be uneconomical. However, the process can remove 75-80% of the SO2 in the flue gas from a low sulfur coal or lignite thereby achieving quite low SO2 emission rates economically while yielding all of its other benefits. For this reason, and its low water use, the process will be quite desirable in many western power plants using low sulfur, low BTU coals which, because of the 1977 amendments to the Clean Air Act, must also employ some SO2 control technology. The process can also use sodium reagents such as Trona, or sodium carbonate. When sodium is used, it would be possible to add a regenerative system at a time which would recycle the sodium reagent and produce elemental sulfur as a by-product. We have recommended to EPA that the percent removal requirement be established at 75-80% and that the floor be revised to 0.5-0.6 lbs. SO2 per million BTU. We have attached three charts comparing our proposed alternative to EPA's proposed 90% removal requirement. Table 2 analyzes the impact of a power plant burning a 10,000 BTU per pound coal. Even with the Wheelabrator-Frye proposal, a power plant would still have to employ some control technology. Graph 2B indicates the differences in removal efficiency among the present standard, the EPA 90% proposal, and our proposed alternative. Finally, Graph 2B compares the actual differences in SO2 emissions resulting from the three approaches. We believe these charts illustrate why the difference between the EPA's and our proposal are not significant. benefits that would accrue from allowing the use of our dry scrubber system more than outweigh any difference in air pollution removal. The We feel that the above recommendations could provide an atmosphere which would allow this and other newer technologies to be used and improved. Moreover, it would provide industry with an alternate to wet scrubbers and thereby encourage industry to convert from oil and gas to coal. systems. The Nation needs alternatives to the present wet scrubber EPA's actions on NSPS are a key element in developing these alternatives. A flexible approach that recognizes all of the environmental impacts of each technology is the only sensible way to proceed. |