Vogelbusch’s continuous fermentation is highly reliable and achieves high alcohol concentrations and excellent yields continuously over extended periods of time.
The MultiCont© process was introduced to the alcohol industry back in 1970 with resounding success. The process has since been refined, and it is now considered the state-of-the-art technology for alcohol and bioethanol fermentation.
The fermenting mash flows steadily through a series of four to seven fermenters, while the alcohol increases in concentration.
A constant flow of substrate enters the fermentation unit and the same volume of mash leaves the system simultaneously.
As soon as the system is in an equilibrium, level and temperature are automatically controlled and operator supervision is reduced to a minimum.
To promote yeast growth, nutrients and air are added to the first fermenters. Agitators in all fermenters ensure proper mixing to avoid sedimentation of suspended materials and yeast cells.
In the last fermenters saccharification of starch and transformation of fermentable sugars into ethanol is completed. The alcohol mash is then fed to an intermediate tank for distillation.
The largest fermentation cascades consist of fermentation tanks with volumes of up to 5,000 m³.
Compared to simple batch processes, Vogelbusch MultiCont© continuous alcohol fermentation is characterized by
Less fermentation volume is required due to significantly less cleaning frequencies and preparation time. Heat exchangers are designed to match the heat load demands at each stage of fermentation. This results in less total heat exchanger area.
The steady-state character of the process reduces the necessity for automated sequences as well as the demand for single control loops and automated valves.
Compared to batch systems, this results in approximately 20 % less investment costs for the MultiCont© fermentation.
Since the process runs at steady state conditions, less manpower is required for periodic sampling and monitoring, bringing down the operator costs by minimum 50 %.
Yeast is self-sustaining after initial inoculation of the system. Chemicals consumption for CIP is less due to considerably lower fermenter and cooler cleaning frequency, thus also reducing the evaporation load of the overall process. By comparison to batch fermentation, costs for chemicals and yeast are more than 90 % less.
Permanent alcohol protection at even the first fermentation stages minimize contamination risks. Furthermore, continuous processes react very slowly. Consequently, changes in the process can be monitored easily and counteractive measures can be taken early.
Due to low contamination risks and stable process conditions a constant product quality can be achieved. Additionally the byproducts DDGS and CO2 can be obtained at consistent quality as process fluctuations are minimal.
Moreover, the lower consumption of caustic for CIP decreases the sodium content in the DDGS.
While continuous systems are generally cheaper and easier to operate, batch systems are often preferred for highly inhibiting substrates (e. g. low-grade molasses) or in conditions requiring a frequent switch between feedstocks (e. g. molasses vs. grain).
Vogelbusch designs both systems and offers flexible plants for switching between continuous and batch fermentation.
