Multi-effect evaporation and thermal or mechanical vapor re-compression systems allow a more effective use of energy. Advanced thermal integration techniques such as heat integration of the evaporation with other process groups can further reduce the primary energy demand considerably.
To minimize steam consumption evaporation plants are often designed as a cascade, with each effect heating the next with its vapors. Depending on the product characteristics and available utilities up to nine effects can be attained by recycling the heat input.
These systems are also suitable when low pressure (waste) steam or other heating sources (e.g. exhaust vapors from a dryer) are available at site. With the corresponding measures integrated grain alcohol plants can be brought down to even zero life steam demand.
If steam with higher pressure is available the thermal vapor recompression system ensures lower steam and cooling water consumption in the multi-effect evaporation.
Based on the principle of a heat pump, MVR systems use electricity and a fan or a turbo-compressor to run the evaporation process. With negligible consumption of steam and cooling water MVR systems are an economic alternative especially for solutions with low concentration and low boiling point elevation.
Therefore MVR systems are often seen as pre-evaporators in a complex evaporation unit, while the final concentration is often reached in a multi-effect evaporator.
Aiming at lowest possible energy demand, our design considerations also cover the thermal integration of the evaporator within the complete production facility by reusing waste heat from other process groups.
A standard solution in Vogelbusch alcohol plants is the reuse of drier vapors for heating the multi-effect stillage evaporator. By this design the demand of life steam for the evaporator can be reduced to zero.
Alternatively the coupling of distillation/rectification with the evaporator also leads to a significant reduction of steam demand for the concentration of stillage or vinasses.
Also flash vapors as always available in sweetener or alcohol plants are a valuable source for heating product or effluent evaporators.
We offer proprietary evaporation systems that are customized to the required plant specifics.
Read more about our » Evaporator design concepts
