The purpose of this project was to develop a preliminary design of a grassroots plant for the production of nylon 6,6 near Calvert City, Kentucky. The yearly production rate of nylon 6,6 was specified at 85 MM lbm/yr. Nylon 6,6 is formed via a polycondensation reaction between adipic acid and hexamethylenediamine. Chains of nylon 6,6 lengthen via step-growth polymerization and the addition of new molecules to the end of each polymer chain.

The preliminary design for the grassroots process involves a pump, two heat exchangers, two reactors, a process vessel, an air cooler, and an extruder. The selected process involves a batch reactor in series with a CSTR in order to maximize polymerization and nylon 6,6 production. The design will produce nylon 6,6 chains with a degree of polymerization of 202. To produce the 85 MM lbm/yr of nylon 6,6, the design will require approximately 55.1 MM lbm of adipic acid, 43.9 MM lbm of HMDA, and 5.2 MM lbm of water each year for the reactants. The nylon 6,6 will be packaged and sold for $1.45 per pound on average. Expected annual revenue for the grassroots plant is expected to be $123.3 million in today's dollars. The design has a total capital investment of approximately $4.03 million, including contingency, fees, and a grassroots factor. Manufacturing costs, including the costs for raw materials, are estimated to be $89.3 million per year. Capital and manufacturing costs are estimated in today's dollars. The process was also designed for a 67% turndown case. This turndown case will cost $59.8 million in manufacturing costs per year and has an expected annual revenue of $82.6 million per year.

Economic evaluation over a ten-year period indicates that the design will have a net present value of $73.36 million at a minimum rate of return of 15%. The expected DCFROR is 5.17%. Construction will begin in Quarter 4 of 2018, and startup is scheduled to take place on June 30, 2019. Upon evaluating the sensitivity, it was found that the sale price of nylon 6,6 has the largest effect on the economics of the design. The proposed design will require 8 plant operators in order to keep the unit running continuously and will cost $775,000 in salary per year. Any safety risks have been accounted for, and a Hazard Operability study was completed.

The design team recommends proceeding with the detailed design phase for the grassroots facility. Equipment layout, including piping and elevation, will need to be completed in order to finalize the equipment sizing and designs. Several assumptions were made in the design process and in the estimation of costs. Therefore, a more thorough design and costing analysis should be completed in order to verify these assumptions during the detailed design.