German bioethanol plant chooses AlfaCond for process flexibility

In 2006, an increase in condensation capacity was needed on a final ethanol condenser. Because of the limited space for installation, extending of the existing shell-and-tube heat exchangers (STHE) was not an option.

AlfaCond, easy to transport and install

Project Manager, Dr. Angermann, consulted Alfa Laval and CropEnergies purchased an AlfaCond 600 plate heat exchanger for the duty. The decision was strongly influenced by the AlfaCond’s compact shelving and ease of installation. It would have been very complicated to transport and install a bigger STHE condenser into the space available. According to Dr. Angermann, the one large inlet connection of the AlfaCond made pipework much simpler. Other important factors were the AlfaCond’s extension flexibility and the lower pressure drop on the vapour side due to the special design of the AlfaCond in comparison with a normal plate heat exchanger.

CropEnergies Bioethanol plant in Zeitz, Germany, currently has a total capacity of 360,000 m3 of ethanol per year.

Flash condenser required for evaporation system

Satisfied with the performance of the AlfaCond 600, Dr. Angermann consulted Alfa Laval again a year later. At the Zeitz plant an evaporation system is used for concentrating stillage, which afterwards is dried and sold as animal feed. The requirement was to install a small flash condenser to balance the vapour load to the final evaporators.

The compact design and thereby low weight in comparison to STHE were significant factors for choosing a plate heat exchanger. An AlfaCond 400 was installed since the existing 400 mm line could be connected directly to the inlet on the unit.

AlfaCond 800 units installed as purge condensers

In 2007 CropEnergies Bioethanol decided to substitute an existing STHE purge condenser to eliminate a bottleneck in the recovery step of the molecular sieves. As the purge condenser runs under low vacuum, sometimes below 100 mbar, it was essential to install a unit with a very low pressure drop on the vapour side.

In addition, the condenser needed the capability to adapt quickly to changes from the molecular sieves. Otherwise there was a risk of quality impairment of the dehydration process, which is the final step in ethanol production.

Based on positive experience with AlfaCond, Dr. Angermann considered replacing the STHE condensers with plate technology from Alfa Laval. Alfa Laval suggested two AlfaCond 800 units, operating in parallel as one unit, a solution which cost less than purchasing one new STHE condenser.

Yet again, the determining factors for Dr. Angermann were AlfaCond’s large inlet and low pressure drop on the vapour side.

Flexible process solutions vital

It is vital for a young plant like CropEnergies Bioethanol in Zeitz to have flexible process solutions. It is difficult to predict what will happen in the real process in comparison to the theoretical planning. The flexibility and the possibility of extension are big advantages for the AlfaCond plate heat exchangers over shell-and-tube units."
- Dr. Angermann