Once the customers have distilled or purchased the high-proof raw alcohol, if they want to produce anhydrous alcohol for automotive, chemical, pharmaceutical, and cosmetic industries, they must dehydrate the product, i.e. remove as much water as possible to meet composition and quality standards. The technology currently most widely used is the molecular sieves, i.e. the removal of water from alcohol in the vapor phase through absorption on zeolites. This way, we can overcome the azeotrope that water forms with ethanol and reach concentrations up to 99.95% ABV.
Other technologies available for alcohol dehydration are:
- Azeotropic distillation with cyclohexane or ethylene glycol.
- Membrane pervaporation
The separation of solids in a distillery usually means treating the grain - in case of distillation "on the grains" - when cereals are used as raw material. By using various machines and technologies, it is possible to separate solids (grits) from the liquid (thin stillage), with the final purpose of obtaining DDG (Distiller's Dried Grains) and DDGS (Distiller's Dried Grains with Solubles), according to whether a concentrator and a dryer are integrated with the process.
DRYING AND PELLETIZING
Ingrain distilleries, the production of DDG and DDGS is of great interest because it is an economically attractive product.
The dryer reduces the humidity of DDG and DDGS up to about 10-15%, lengthening the shelf life of the product and providing greater logistical flexibility. The most frequently used type of dryer is the rotating drum dryer with hot air: the product to be dried is placed in a rotating drum where it touches the air that has been heated thanks to a burner, usually methane. The product obtained keeps excellent nutritional properties.
Depending on the market, the dried DDG and DDGS can be compressed into pellets and bagged for shipment.
BIOGAS: WHOLE STILLAGE AS A SUBSTRATE FOR BIOGAS PRODUCTION
The liquid effluent from the distillation process, commonly known as “stillage”, is a valuable stream that can be recovered for obtaining biogas, by secondary anaerobic fermentation). This recycling process is advantageous because can convert a liquid with high content of organic matter, which would otherwise need to be disposed, into biogas in sufficient quantity to supply from 40% to 100% of the distillery’s thermal energy requirements. In addition, it is possible to generate large amount of “green” electricity to be sold on the grid.
Another co-product from the biodigestion process is the residue from the anaerobic fermentation (digestate), which can contain up to 5 kg/m3 of nitrogen and can be sold as inorganic fertilizer.
We will help you design, build and commission your biogas plant, as well as calculate the logistics of stillage and digestat (digested residue) for you.