Waste Stream Incineration Results in Combustion in Decoke Piping

摘要

Prevention of Process fires is critical to successful and safe operation of any Chemical Plant. Ethylene plants generate various small waste gas streams that must be collected and recycled or incinerated to minimize VOC emissions and to ensure that these waste streams do not create hazards that could result in unintended combustion. In many cases multiple process systems and streams are connected to one common disposal system and innovative methods have been developed to ensure destruction of the various compounds. The design and operation of these systems warrant very close scrutiny as the multitude of scenarios created may result in some very unexpected problems including unplanned combustion events. This paper describes a series of incidents resulting from the operation of such a disposal system. The incidents occurred during two separate plant outages at the Nova Chemicals Ethylene 3 plant at Joffre, Alberta, Canada. In each case the system was being operated under very low load with some of the normal components absent from the combined waste stream. Background is provided on the disposal system process and how it influenced the events. The incident investigations, conclusions, and mitigation are explored as well as some of the present and future challenges that may be ahead with operating this type of system as part of an integrated Ethylene plant.