Uniformity of distribution of anhydrous ammonia into shelled corn in a continuous ammoniator.
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 2.3 kg/min (5 lb/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.