Submitted to: Transactions of the ASABE
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/3/2006
Publication Date: 3/3/2007
Citation: Taylor, F., Kim, T.H., Goldberg, N.M., Flores, R.A. 2007. Uniformity of distribution of anhydrous ammonia into shelled corn in a continuous ammoniator. Transactions of the ASABE, 50(1):p.147-152. Interpretive Summary: Fuel ethanol is produced from corn in fermentors, where yeast cells consume the glucose sugar that comes from the starch in the corn. However, ethanol produced this way is too expensive to compete directly with gasoline. It has been suggested that the cost of producing fuel ethanol can be reduced by treating corn with anhydrous ammonia. By loosening the outer covering (hull) of the corn kernel, this treatment makes it easier to separate and recover valuable co-products, the sale of which will reduce the net cost of corn. This, in turn, will significantly reduce the overall cost of producing ethanol from corn. In this paper, the design, construction and testing of a device to continuously and evenly treat corn with ammonia are described. Application of this technology will benefit ethanol producers, corn growers, transportation fuel consumers and taxpayers.
Technical Abstract: Cost-effective recovery of non-fermentable, insoluble parts of the corn kernel before fermentation may increase the efficiency of fermentation and lower the overall cost of producing ethanol fuels. The non-fermentable hull can be loosened with hot alkali (alkali debranning). Gaseous ammonia may be a cost-effective substitute for hot alkali. Up to 1000 mg ammonia N per kg of corn also satisfies the nitrogen requirement for optimal yeast fermentation. Treating corn with ammonia is technically difficult because the absorption of ammonia is rapid and exothermic. A device to continuously and evenly treat 5 lb/min (2.3 kg/min) of corn with ammonia gas (1000 mg N per kg corn) was designed, built and tested. Ammonia was trapped and recycled within the treatment section of the ammoniator by continuous flow of air and buffer. The residence time in the treatment section was approximately 8 minutes. Testing showed that it was necessary to process at least 300 lb (135 kg) of corn through the device to achieve steady state. Ammonia was more evenly distributed into the corn when mechanical vibration was employed to promote even flow of corn through the ammoniator.