Popcorn seeds and metal passivation, traditionally by sodium nitrite, are widely used in the butadiene industry to control fouling. Unfortunately, sodium nitrite presents safety and environmental hazards, has stringent temperature and pH requirements, and is expensive to dispose of. To overcome these limitations, Nalco Champion developed an effective, nontoxic passivation technology which has been adopted by butadiene producers globally.
Unwanted polymerization (fouling) during butadiene purification is a constant challenge for plant operators. During new equipment commissioning or turnaround, carbon steel equipment (tanks, towers, packing, pumps, exchangers, lines, etc.), can develop a red surface rust coating. Red rust (haematite) accelerates the breakdown of peroxides to peroxy radicals that serve as polymerization initiators.
Another problem encountered in areas where butadiene concentrates, such as the purification section of a butadiene plant, is the presence of popcorn polymer. Popcorn polymer contains active free radicals in the polymer matrix. If not passivated or “killed,” residual popcorn polymer remaining in the tower can promote further popcorn growth.
Nalco Champion passivation technology is:
Effective at low temperatures
Easy to apply
Easy to monitor
The Nalco Champion passivation procedure includes two steps. The first step is popcorn polymer passivation with an effective popcorn polymer inhibitor. The second step, using the Nalco Champion non-toxic metal passivator, converts the red rust to black rust (magnetite), deactivating the red rust.