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Show An investigation of the causes of the feed shutdowns in the 1988 period was conducted. The various operation records chronicling the operation were examined. It was found that, many (10) of the occurrences could be attributed to a malfunctioning of the oxygen analyzer. Ten of the feed shutdowns were innocuous. For example, there were five feed shutdowns on 7/9/88, in which, SCC excess oxygen levels dropped below the 4: percent limit to the 2-3 percent range without the occurrence of CO spikes. An examination of the stripcharts revealed that the excess air levels in the SCC (provided by two air burners) were about 5 percent, which was too low to provide sufficient margin for fluctuation. In addition, three shutdowns were caused by a SCC burner failure. The causes for the two remaining occurrences can not be ascertained due to lack of data. WESTON TRANSPORTABLE INCINERATION SYSTEM Roy F. Weston, Inc. (WESTON) owns and operates a trans}X)rtable incineration system (TIS) to treat solids contaminated with hazardous materials such as organic compounds and polychlorinated biphenyls (PCBs) (22). The TIS employs a two-stage combustion process for incineration of solid wastes. The primary incineration chamber consists of a rotary kiln; the secondary combustion chamber is an afterburner. Flue gas exiting the afterburner is treated by a pollution control system that removes particulates and neutralizes acidic gases. The treated flue gas is discharged to the atmosphere. The TIS is designed to accommodate a maximum heat release of 9. 7 MW (33 million Btu/hr) . The rotary kiln is designed to provide a minimum of 30 min. of soil retention time. The kiln is designed to dry and to heat the feed material to 1800oF; however, lower operating temperatures can be accommodated. The secondary combustion chamber is designed to provide a minimum gas retention time of 2 seconds. The TIS recently completed remediation of an abandoned salvage yard in Beardstown, IL. More than 8500 tons of PCB-contaminated soil were treated successfully using the TIS. The unit is currently operating at a hazardous waste site in Chicago, IL. A minimum of 16,000 tons of sludge and soil contaminated with a wide range of RCRA wastes is being treated. The processed material will be used for on-site backfill. The oily sludge and highly contaminated soil have a heating value ranging from 500 to 6000 Btu/lb (average 2900 Btu/lb). These materials are ram-fed into the rotary kiln about every minute. The original air-based TIS had difficulty in burning these materials smoothly. Excursions of high CO concentration had caused frequent waste feed shutdown and process interruption. The CO problem also limited the throughput of the TIS. In addition, temperature excursions of the combustion chambers had caused serious slagging problems. Confronted with these challenges, Weston engineers promptly decided to apply oxygen lancing technology supplied by Linde. Upon sanction from the illinois Environmental Protection Agency, two independent LINDE Oxygen Lancing Systems (OLS) were installed, one each for the rotary kiln and the secondary eombustion chamber as shown in Figure 6. The kiln oxygen system serves to improve the ash quality by improving the kiln temperature distribution. The - 11 - |