(8j) Modeling and Simulation of 1,3 Butadiene Extraction Process at Turndown Capacities

1,3-butadiene is required in the manufacture of various materials and chemicals for applications in a wide range of industries such as healthcare, automotive, building and construction and consumer durables [1]. It is mainly used in the production of polybutadiene rubber, styrene-butadiene rubber (SBR), styrene-butadiene latex, nitrile butadiene rubber (NBR), acrylonitrile-butadiene-styrene resin (ABS), chloroprene rubber, etc. Almost all 1,3- butadiene is produced from steam cracking processes. Heavier cracker feedstocks produce more butadiene than the lighter ones. As the cracker feedstock around the globe is trending towards the lighter feedstocks because of the less expansive ethane produced from shale gas, the sustained production of 1,3-butadiene in olefin plants is facing big challenges. This causes not only a decrease in butadiene supply, but also forces various butadiene production facilities to run either at reduced capacities or at turndown capacities. As per the current market trends in North America and Europe, 1,3-butadiene production is expected to continue to decrease for next several years [2].

In this paper, steady state and dynamic models have been developed in the Aspen Plus (V10) framework to produce 1,3-butadiene using N-methyl-2-pyrrolidone (NMP) as a solvent at turndown ratios of feed rates in an olefin plant. In this study, various offset conditions were simulated, and response of plant was observed, recorded and based on observations, suggestions were made for process optimization.

In this process, the mixed feed and the NMP solvent first go through a series of columns where extractive distillation is utilized to separate the butanes, butenes and acetylenes. The vapor product from the extractive distillation goes to another series of distillation columns and is purified to the required purity. The bottom product of the extractive distillation column, which is mainly NMP solvent with traces of hydrocarbons, is purified and recycled to the first and third extractive distillation columns. The maximum operating feasibility to attain on-spec product of the extraction process is examined via parametric analysis in steady-state simulations. The optimal operating status and control strategies under various facility capacities are studied via dynamic simulations.

References

1. 1,3 Butadiene (BD) Market Analysis by Application (Butadiene Rubber, ABS, SBR, SB Latex, NBR, Hexamethylenediamine), Bio-based Opportunities and Segment Forecasts To 2020. (http://www.grandviewresearch.com/industry-analysis/butadiene-market)
2. The Continuing Quest for Butadiene by Jeffrey S. Plotkin. (https://www.acs.org/content/acs/en/pressroom/cutting-edge-chemistry/the-continuing-quest-for-butadiene.html)
3. Butadiene Extraction Technology overview by CB&I.
4. Kindler and H. Puhl, US Patent, 6,337,429, B1 (2002).
5. Saffari, F. Abbasi, F. Jalali-Farahani and N. Mostoufi, Proceed. 2005 Inter. Conf. Sim. Modeling, Thailand (2005).
6. Kim Y H, S Y Kim, B S Lee, Simulation of 1,3-butadiene extractive distillation process using N-methyl-2-pyrrolidone solvent. Korean J. of Chem. Eng., 29(11), 1493-1499 (2012).