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Title: PRETREATMENT OF WHOLE CORN KERNELS IN A CONTINUOUS AMMONIATOR

Author
item Taylor, Frank
item Kim, Tae Hyun
item Goldberg, Neil

Submitted to: Transactions of the ASABE
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/7/2007
Publication Date: 3/1/2007
Citation: Taylor, F., Kim, T., 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, fuel 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 the whole corn kernels with anhydrous ammonia. Added ammonia provides nitrogen for yeast nutrition, and this pretreatment may help to separate and recover valuable co-products from the process. Removing these non-fermentable coproducts of the kernel will also improve the fermentation process, and the sale of co-products will reduce the net cost of corn. This, in turn, may significantly reduce the overall cost of producing ethanol from corn. In this paper, the design, construction and testing of the world's first pilot scale 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. Treating whole corn with ammonia gas may weaken the physical structure of the kernel, and improve grinding and separations sufficiently to make fractionation of the non-fermentable components of the kernel cost-effective. The quick and even distribution of a controlled amount of ammonia into a batch of corn is problematic 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 feeding continuous streams of buffer solution and air flowing counter-current to the corn through the device. The kernel residence time in the treatment section was approximately 8 min. An assay for the ammonia content of individual corn kernels was developed and the standard deviation among kernels from samples of ammoniated corn showed that ammonia was much more evenly distributed in the continuous ammoniator than in a bench-scale batch ammoniator.