(159a) Study On Flare Minimization During Ethylene Plant Upsets

Process upsets mean facilities run in an unstable or an undesirable situation that may jeopardize product quality and/or plant safety. During the ethylene production, plants might experience various process upsets. Some are significant and others are minor, and the majority contributions to flaring emission are from acetylene reactor effluent and ethylene splitter. To reduce the flaring caused by process upsets, recycling off-spec materials to the upstream process for reprocessing presents a good choice. Two major options are available to routine the off-spec components: one is to line the recycle to the CGC suction, and the other is to tie it to the furnace feed. Establishing these two recycles presents a promising way and brings a lot of benefits, which include reducing flaring emission, reducing fresh feedstock, increasing the tolerance of the process when facing upsets, avoiding unnecessary plant shutdowns and subsequent startups, saving energy and fuel, etc.

This paper conducts quantitative study to help plants minimize flaring without sacrificing safety during process upsets. As the two recycles have their limits, they should be implemented carefully. Considering their limits and safety issues, various upset scenarios are extensively analyzed. Dynamic simulation-based solutions are provided accordingly, such that efficient and effective ways can be taken to reduce upset related flaring.