AIChE 2017 Student Design Competition: Manufacturing facility for Nylon 6 6

Abstract

A preliminary design and economic analysis was performed for the development of a grass roots manufacturing facility of Nylon 6 6 in Calvert City, Kentucky. Nylon 6 6 is a polymer that is synthesized from Adipic Acid (ADA) and Hexamethylene diamine (HMDA) through polycondensation and step-growth polymerization reactions. The two reactions pursued were batch and continuous processes, in which Nylon 6 6 was sold either in solid pellet or spun fiber form. Additionally, the process yields a byproduct of 1,6 hexanediamine (diamine). The objective of the project was to determine which of the four production methods served as the most economically viable option. The optimum Nylon 6 6 production design is an intricate balance between capital and operating expenses that maximizes revenue and minimizes costs.

Given the opportunity to invest in the generation of a grass roots facility, it is our recommendation to proceed with the production of spun Nylon 6 6 fibers using a continuous production process. The economic analysis determined which option was the most economically viable for the company to invest in. From this point, a series of optimization procedures took place to reduce utility and capital costs in an effort to maximize annual profits and reduce the payback period of the project. Through changes in the maximum temperature of the evaporation unit within an acceptable range, capital costs and utility costs were reduced resulting in the lowest PWC. The evaporation unit temperature of 280 degrees Celsius was determined to be the most economical case for this production process, with a capital investment of $13,015,000, a DCFROR of 211%, breakeven processing cost of $2.40, and an NPV of $17,874,000. It was determined advantageous to continue with project development; therefore, the project is scheduled to be completed and fully operational in June of 2018 and will have a payback period of 1.57 years.

The fundamental safety concept for this process was to make the operation inherently safer and to mitigate hazards. The hazardous components present in the process consist of ADA, HMDA, and diamine. The risks associated with these components include possible combustion, irritation to respiratory system and skin, and hazardous release to the environment. To mitigate these risks, it is recommended that the equipment is designed to operate within specified design temperatures and pressures and to implement a Distributed Control System (DCS).