OCR Text |
Show Throughput Increase The maximum contaminated soil throughput of the Mobile Incineration system during its operation with air burners had been 2000 Ib/hr. However, this maximum rate was not sustainable. For example, the average throughput rate of four test runs in the Spring of 1985 had been only 1478 lb/hr. With the Linde Oxygen Combustion System, the MIS achieved a sustainable soil throughput rate of 4000 lb/hr, as confirmed by a certified verification test. The comparison of the two sustainable conditions is shown in Table I. With normal and relatively dry (about 20'- moisture) soil, it was found quite easy to feed up to 5,000 lb/hr. Although the ram feed system had trouble processing muddy soil, the kiln and SCC operated well with it. Due to the significant reduction in kiln combustion gas velocity. as shown in Table 1, and the addition of a cyclone, the dust carryover problem was totally eliminated . It has been demonstrated that very light (4 lb/cu ft) vermiculite can be processed through the system at a capacity up to 7.4 cu yd/hr (800 lb/hr). The particulate carryover was less than 15'- of the feed rate and it was easily removed by the cyclone. It should be noted that the current capacity limitation of the MIS is about 5000 Ib/hr of soil, mainly due to the mechanical limitations of the rotary kiln (which could be upgraded). It is not due to heat transfer or flue gas volume limitations. The kiln limitation can be solved by, for example, using two or more transportable rotary kilns to feed the common downstream equipment. It is estimated that up to 10 TPH of soil can be handled by such an upgraded system. Such a throughput increase would make mobile incineration technology more economically attractive. This impact of using oxygen for throughput increase would be substantial in any system. In the case of a mobile or transportable incineration system which is restricted in size. a higher throughput is even more important. with comparable capital investments, the oxygen system can potentially process several times the throughput of an air system. Fixed operating costs can be spread out over a much larger quantity of wastes processed per year. In addition, the oxygen-based system will offer the benefit of a much shorter cleanup time, which is very desirable from the point of view of the pUblic. For existing stationary incinerators, it is also technically feasible and economically attractive to utilize an oxygen-based combustion system to increase the throughput. It could not only cut down the lead time to achieve a capacity increase, but also negate the need for the large capital expenditure of entirely new incinerators . Kiln Puff Reduction When high-BTU wastes are fed into rotary kiln incinerators in an intermittent mode. the transient combustion behaviors of these materials create unsteady releases of combustible gases which may momentarily deplete the oxygen supply to the incinerators. These temporary oxygen-deficient conditions could cause the release of products of incomplete combustion (PICs) and often called kiln "puffs". These "puff" phenomena have raised public concerns recently and have been the subject of research projects sponsored by the EPA[6&7). - 4 - |