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Show INTRODUCTION This paper reports on the field experience with a novel method for the enhaneed control of transient emissions from rotary kiln incinerators using oxygen enrichment. This method was implemented through the use of the LINDE Oxygen Combustion System (OCS) that was installed on the EPA Mobile Incineration System (MIS) and the LINDE Oxygen Lancing System (OLS) that was installed on Weston's Transportable Incineration System (TIS). A review of the MIS operating data with regard to the frequency of feed interruptions due to low oxygen or high carbon monoxide content in the flue gas before and after installation of the Linde OCS was conducted. The review showed that for operating periods of approximately equal duration and with equivalent feeds, the occurrence of these interruptions decreased by over 58% with the use of the Linde OCS. Similar bebefits were also realized on the Weston TIS. BACKGROUND Modern incineration technology represents a proven way to destroy a wide range of organic hazardous wastes. EPA studies have shown that well-run conventional incineration systems achieve very high destruction and removal efficiencies (DREs) of principal organic hazardous constituents (POHCs)(!,~). However, one of the current major public concerns about incineration is the emission of products of incomplete combustion (PICs), even though emission of PICs occurs from all combustion sources. Current test data indicate that the PIC levels for well-designed and operated incinerators are in the parts -per-billion level (2). On the other hand , EPA studies and pilot scale tests also show that the performance of incinerators may deteriorate significantly during some upset conditions (also called "failure modes") (~,!). Failure modes of significant concern include the occurrence of flameout, poor atomization, low combustion temperature, and feed overloading. These failure modes may result in unacceptably low destruction of POHCs and significant releases of PICs. Another failure mode of significant concern is the transient emission of products of incomplete combustion (PICs) from incinerators. When high-heat-content wastes are fed into rotary kiln incinerators (or other batch-fed incinerators) in an intermittent mode, the transient combustion behavior of these materials creates unsteady releases of combustible gases which may momentarily deplete the oxygen supply to the incinerators. These low oxygen or oxygen-deficient conditions could cause the transient release of PIes, which are often called kiln "puffs." This phenomenon has been the subject of several recent EPA studies (~) and it is one of the concerns receiving much attention from the public. The EPA has proposed incineration rule amendments to control emissions of PICs. Given that carbon monoxide (CO) is a conservative indicator of combustion upset, the Agency believes that controlling CO is a prudent and reasonable approach to minimize the potential risk from PICs (7). MEASURES TO CONTROL TRANSIENT EMISSIONS To avoid these upset conditions, extreme caution is required in the operation of the system. An ASME Research Committee has published a technical guide with numerous operational suggestions (~) to help incinerator operators address this issue. Common measures to control transient emissions are discussed below. - 2 - |
