Modeling and Simulation of the 1,3‐Butadiene Extraction Process at Turndown Capacity

• Published in: Chemical engineering & technology Vol. 42; no. 12; pp. 2649 - 2657
• Main Authors: Tripathi, Namit, Xu, Qiang, Palanki, Srinivas
• Format: Journal Article
• Language: English
• Published: Frankfurt Wiley Subscription Services, Inc 01-12-2019
• Subjects: 1,3‐Butadiene; Butadiene; Chemical industry; Computer simulation; Controllers; Dynamic simulation; Extractive distillation; Feed rate; Flow velocity; Purity; Solvents; Variations
• ISSN: 0930-7516; 1521-4125
• DOI: 10.1002/ceat.201900019

As cracker feed around the globe is trending towards lighter feedstocks, butadiene production facilities worldwide are now run at turndown capacities. Models are developed to study how operation at turndown ratios of feed rates affects the purity of 1,3‐butadiene. The optimal solvent‐to‐feed ratio was found to be in the range of 6–7 when the plant is run at normal throughput; however, it is necessary to change the solvent‐to‐feed ratio in the range of 10–11 when the plant is operating at turndown capacity. Dynamic simulations indicate that the effect of fluctuations in the feed flow rate on product purity can be minimized by a ratio controller to change the solvent flow rate and a composition controller to alter the side‐draw flow rate.
Steady‐state and dynamic models were developed to study how operation at turndown ratios of feed rates affects the purity of 1,3‐butadiene using N‐methyl‐2‐pyrrolidone as solvent in an olefin plant. Appropriate control schemes are created to maintain the product purity in view of fluctuating feed flow rates which can be minimized effectively by a ratio controller and a composition controller.