Title: Unit 12 Readings and Lecture
Course: BFM 201 Ethanol Production > Section: BFM 201 Ethanol Production

Unit 12 Readings and Lecture

To Do:
Read Textbook: Ethanol Process Fundamentals – Chapter 8 pages 8.1 – 8.7
The evaporation process in my mind exemplifies the truly circularity of the ethanol process, the goal to reuse and reclaim as much of the production material not consumed after making ethanol. This would include the whole stillage, which is full of fat, protein, fiber, and minerals left behind after the starch has been fermented. It also includes process water and thermal energy. During the evaporation process the facility is striving to prepare co-products that are important to the profitability of the plant. Of particular interest is the preparation of the Dried Distillers Grain with Syrup. Additionally, the facility is reclaiming process water and thermal energy both of which contribute to the profitability and sustainability of the plant.

The evaporation process involves two distinct technologies to separate solids and liquids. The first step – and the step covered in this unit – is centrifuge separation which is a mechanical step utilizing the properties of specific gravity and separation force.  Two important products from this step are wet cake and thin stillage. The wet cake will be sold as wet distillers grain or further dried and sold as dried distillers grain. Approximately 50% of the thin stillage will be used as backset going back to cook water. The backset is used to save water, time, and cost of evaporating all the water for the process and is a good nutrient source for the yeast in the fermenters.

The second step – discussed more during the next unit – is the evaporation system which works on the principle of difference in boiling points for substances. Two important products from this step are syrup and flash vapors. Approximately 50% of the syrup will be added to the dried distillers grains and 50% sold as a high value protein. The flash vapors will be reused in the evaporators or condensed into cook water to be used in the slurry blender with the backset.

The ethanol production process can be broken down into the “front end” where we have made the ethanol and the “back end” where we are preparing the co-products and reusing water and thermal energy to be reused in the “front end." This is what I mean by circularity.
References:

Chapter 8 (2006). In Ethanol process fundamentals: An introduction to ethanol processing. Granite Falls, MN: Minnesota Energy Enterprise Center.

Jacques, K. A., Lyons, T. P., & Kelsall, D. R. (2003). Chapter 26. In The alcohol textbook: A reference for the beverage, fuel and industrial alcohol industries. Nottingham: Nottingham University Press.