Engineering process and cost model for a conventional corn wet milling facility

Conventional wet milling of corn is a process designed for the recovery and purification of starch and several coproducts (germ, gluten, fiber and steep liquor). The total starch produced by the wet milling industry in the USA in 2004 equaled 21.5 billion kg, including modified starches and starches used for sweeteners and ethanol production. Process engineering and cost models for a corn wet milling process (for steeping and milling facilities) have been developed for a "generic" processing plant with a capacity of 2.54 million kg of corn per day (100,000 bu/day). The process includes grain cleaning, steeping, germ separation and recovery, fiber separation and recovery, gluten separation and recovery and starch separation. Information for the development of the models was obtained from a variety of technical sources including commercial wet milling companies, industry experts and equipment suppliers. The models were developed using process and cost simulation software (SuperPro Designer^®) and include processing information such as composition and flow rates of the various process streams, descriptions of the various unit operations and detailed breakdowns of the operating and capital cost of the facility. Based on the information from the model, we can estimate the cost of production per kilogram of starch using the input prices for corn and other wet milling coproducts. We have also used the model to conduct a variety of sensitivity studies utilizing modifications such as feedstock costs, corn compositional variations, and the sale of wet corn gluten feed. The model is also being used as a base-case for the development of models to test alternative processing technologies and to help in the scale-up and commercialization of new wet milling technologies. This model is available upon request from the authors for educational, non-commercial and research uses.